diff mbox series

[f2fs-dev,v3,04/10] fscrypt: Drop d_revalidate once the key is added

Message ID 20240111225816.18117-5-krisman@suse.de (mailing list archive)
State Superseded
Headers show
Series Set casefold/fscrypt dentry operations through sb->s_d_op | expand

Commit Message

Gabriel Krisman Bertazi Jan. 11, 2024, 10:58 p.m. UTC 
From fscrypt perspective, once the key is available, the dentry will
remain valid until evicted for other reasons, since keyed dentries don't
require revalidation and, if the key is removed, the dentry is
forcefully evicted.  Therefore, we don't need to keep revalidating them
repeatedly.

Obviously, we can only do this if fscrypt is the only thing requiring
revalidation for a dentry.  For this reason, we only disable
d_revalidate if the .d_revalidate hook is fscrypt_d_revalidate itself.

It is safe to do it here because when moving the dentry to the
plain-text version, we are holding the d_lock.  We might race with a
concurrent RCU lookup but this is harmless because, at worst, we will
get an extra d_revalidate on the keyed dentry, which is will find the
dentry is valid.

Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>

---
Changes since v2:
  - Do it when moving instead of when revalidating the dentry. (me)

Changes since v1:
  - Improve commit message (Eric)
  - Drop & in function comparison (Eric)
---
 include/linux/fscrypt.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

kernel test robot Jan. 18, 2024, 8:23 a.m. UTC | #1 
Hello,

kernel test robot noticed "BUG:kernel_NULL_pointer_dereference,address" on:

commit: 1cfe4ba685d9eb6123648a0d9bef2d3d57b078ef ("[PATCH v3 04/10] fscrypt: Drop d_revalidate once the key is added")
url: https://github.com/intel-lab-lkp/linux/commits/Gabriel-Krisman-Bertazi/ovl-Reject-mounting-case-insensitive-filesystems/20240112-070113
base: https://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs.git dev-test
patch link: https://lore.kernel.org/all/20240111225816.18117-5-krisman@suse.de/
patch subject: [PATCH v3 04/10] fscrypt: Drop d_revalidate once the key is added

in testcase: fxmark
version: fxmark-x86_64-0ce9491-1_20220601
with following parameters:

	disk: 1SSD
	media: ssd
	test: MWRL
	fstype: xfs
	directio: bufferedio
	cpufreq_governor: performance



compiler: gcc-12
test machine: 128 threads 2 sockets Intel(R) Xeon(R) Platinum 8358 CPU @ 2.60GHz (Ice Lake) with 128G memory

(please refer to attached dmesg/kmsg for entire log/backtrace)



If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202401181648.4192e541-oliver.sang@intel.com


[   73.173380][ T6828] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   73.181338][ T6828] #PF: supervisor read access in kernel mode
[   73.187453][ T6828] #PF: error_code(0x0000) - not-present page
[   73.193566][ T6828] PGD 11cc47067 P4D 0
[   73.197762][ T6828] Oops: 0000 [#1] SMP NOPTI
[   73.202383][ T6828] CPU: 16 PID: 6828 Comm: fxmark Tainted: G S                 6.7.0-rc1-00176-g1cfe4ba685d9 #1
[   73.212818][ T6828] Hardware name: Intel Corporation M50CYP2SB1U/M50CYP2SB1U, BIOS SE5C620.86B.01.01.0003.2104260124 04/26/2021
[ 73.224837][ T6828] RIP: 0010:__d_move (include/linux/fscrypt.h:241 fs/dcache.c:3003) 
[ 73.229912][ T6828] Code: c1 00 00 00 08 0f 84 ed 00 00 00 81 e1 3f 10 07 00 0f 84 e1 00 00 00 80 cc 40 89 c1 81 e1 ff ff ff fd 41 89 4d 00 49 8b 4d 60 <48> 81 39 10 21 4e 81 0f 84 66 01 00 00 83 43 04 01 41 83 45 04 01
All code
========
   0:	c1 00 00             	roll   $0x0,(%rax)
   3:	00 08                	add    %cl,(%rax)
   5:	0f 84 ed 00 00 00    	je     0xf8
   b:	81 e1 3f 10 07 00    	and    $0x7103f,%ecx
  11:	0f 84 e1 00 00 00    	je     0xf8
  17:	80 cc 40             	or     $0x40,%ah
  1a:	89 c1                	mov    %eax,%ecx
  1c:	81 e1 ff ff ff fd    	and    $0xfdffffff,%ecx
  22:	41 89 4d 00          	mov    %ecx,0x0(%r13)
  26:	49 8b 4d 60          	mov    0x60(%r13),%rcx
  2a:*	48 81 39 10 21 4e 81 	cmpq   $0xffffffff814e2110,(%rcx)		<-- trapping instruction
  31:	0f 84 66 01 00 00    	je     0x19d
  37:	83 43 04 01          	addl   $0x1,0x4(%rbx)
  3b:	41 83 45 04 01       	addl   $0x1,0x4(%r13)

Code starting with the faulting instruction
===========================================
   0:	48 81 39 10 21 4e 81 	cmpq   $0xffffffff814e2110,(%rcx)
   7:	0f 84 66 01 00 00    	je     0x173
   d:	83 43 04 01          	addl   $0x1,0x4(%rbx)
  11:	41 83 45 04 01       	addl   $0x1,0x4(%r13)
[   73.249920][ T6828] RSP: 0018:ffa000000a99bce8 EFLAGS: 00010206
[   73.256134][ T6828] RAX: 0000000000480000 RBX: ff1100012cab5380 RCX: 0000000000000000
[   73.264248][ T6828] RDX: ff1100012cab4609 RSI: 0000000000000000 RDI: ff1100012cab4600
[   73.272366][ T6828] RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000020c
[   73.280473][ T6828] R10: ff110001622ddde0 R11: 0000000000010000 R12: 0000000000000000
[   73.288584][ T6828] R13: ff1100012cab4600 R14: 0000000000000000 R15: ff1100012cab5200
[   73.296699][ T6828] FS:  00007f1073011600(0000) GS:ff1100103f600000(0000) knlGS:0000000000000000
[   73.305766][ T6828] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   73.312488][ T6828] CR2: 0000000000000000 CR3: 000000012af2a006 CR4: 0000000000771ef0
[   73.320596][ T6828] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   73.328699][ T6828] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   73.336803][ T6828] PKRU: 55555554
[   73.340485][ T6828] Call Trace:
[   73.343900][ T6828]  <TASK>
[ 73.346960][ T6828] ? __die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434) 
[ 73.350983][ T6828] ? page_fault_oops (arch/x86/mm/fault.c:707) 
[ 73.355957][ T6828] ? exc_page_fault (arch/x86/include/asm/irqflags.h:37 arch/x86/include/asm/irqflags.h:72 arch/x86/mm/fault.c:1513 arch/x86/mm/fault.c:1561) 
[ 73.360837][ T6828] ? asm_exc_page_fault (arch/x86/include/asm/idtentry.h:570) 
[ 73.365974][ T6828] ? __d_move (include/linux/fscrypt.h:241 fs/dcache.c:3003) 
[ 73.370410][ T6828] ? __d_move (arch/x86/include/asm/atomic.h:23 include/linux/atomic/atomic-arch-fallback.h:457 include/linux/atomic/atomic-instrumented.h:33 include/asm-generic/qspinlock.h:57 include/linux/fsnotify_backend.h:580 fs/dcache.c:3002) 
[ 73.374846][ T6828] d_move (include/linux/seqlock.h:500 include/linux/seqlock.h:572 include/linux/seqlock.h:910 fs/dcache.c:3032) 
[ 73.378757][ T6828] vfs_rename (include/linux/fs.h:807 fs/namei.c:4864) 
[ 73.383189][ T6828] ? do_renameat2 (fs/namei.c:4996) 
[ 73.387963][ T6828] do_renameat2 (fs/namei.c:4996) 
[ 73.392568][ T6828] __x64_sys_rename (fs/namei.c:5040) 
[ 73.397336][ T6828] do_syscall_64 (arch/x86/entry/common.c:51 arch/x86/entry/common.c:82) 
[ 73.401835][ T6828] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:129) 
[   73.407817][ T6828] RIP: 0033:0x7f1072e83ed7
[ 73.412325][ T6828] Code: e8 6e 82 09 00 85 c0 0f 95 c0 0f b6 c0 f7 d8 5d c3 66 90 b8 ff ff ff ff 5d c3 66 0f 1f 84 00 00 00 00 00 b8 52 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 89 8f 17 00 f7 d8 64 89 02 b8
All code
========
   0:	e8 6e 82 09 00       	callq  0x98273
   5:	85 c0                	test   %eax,%eax
   7:	0f 95 c0             	setne  %al
   a:	0f b6 c0             	movzbl %al,%eax
   d:	f7 d8                	neg    %eax
   f:	5d                   	pop    %rbp
  10:	c3                   	retq   
  11:	66 90                	xchg   %ax,%ax
  13:	b8 ff ff ff ff       	mov    $0xffffffff,%eax
  18:	5d                   	pop    %rbp
  19:	c3                   	retq   
  1a:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
  21:	00 00 
  23:	b8 52 00 00 00       	mov    $0x52,%eax
  28:	0f 05                	syscall 
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 01                	ja     0x33
  32:	c3                   	retq   
  33:	48 8b 15 89 8f 17 00 	mov    0x178f89(%rip),%rdx        # 0x178fc3
  3a:	f7 d8                	neg    %eax
  3c:	64 89 02             	mov    %eax,%fs:(%rdx)
  3f:	b8                   	.byte 0xb8

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 01                	ja     0x9
   8:	c3                   	retq   
   9:	48 8b 15 89 8f 17 00 	mov    0x178f89(%rip),%rdx        # 0x178f99
  10:	f7 d8                	neg    %eax
  12:	64 89 02             	mov    %eax,%fs:(%rdx)
  15:	b8                   	.byte 0xb8
[   73.432265][ T6828] RSP: 002b:00007ffe3fb6db98 EFLAGS: 00000202 ORIG_RAX: 0000000000000052
[   73.440777][ T6828] RAX: ffffffffffffffda RBX: 00007f107300d840 RCX: 00007f1072e83ed7
[   73.448853][ T6828] RDX: 0000000000000000 RSI: 00007ffe3fb6eba0 RDI: 00007ffe3fb6dba0
[   73.456921][ T6828] RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffe3fb6d937
[   73.464983][ T6828] R10: fffffffffffffa2e R11: 0000000000000202 R12: 000055ef6a56d0a2
[   73.473046][ T6828] R13: 00007ffe3fb6eba0 R14: 00007ffe3fb6dba0 R15: 00007f1073004000
[   73.481105][ T6828]  </TASK>
[   73.484219][ T6828] Modules linked in: xfs loop btrfs blake2b_generic xor raid6_pq libcrc32c sd_mod t10_pi crc64_rocksoft_generic crc64_rocksoft crc64 sg intel_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel sha512_ssse3 rapl intel_cstate ast ahci libahci ipmi_ssif mei_me acpi_ipmi ioatdma drm_shmem_helper intel_uncore i2c_i801 dax_hmem ipmi_si libata drm_kms_helper mei joydev i2c_smbus dca intel_pch_thermal wmi ipmi_devintf ipmi_msghandler acpi_pad acpi_power_meter drm fuse ip_tables
[   73.538153][ T6828] CR2: 0000000000000000
[   73.542418][ T6828] ---[ end trace 0000000000000000 ]---
[   73.560053][ T6828] pstore: backend (erst) writing error (-28)
[ 73.566136][ T6828] RIP: 0010:__d_move (include/linux/fscrypt.h:241 fs/dcache.c:3003) 
[ 73.571178][ T6828] Code: c1 00 00 00 08 0f 84 ed 00 00 00 81 e1 3f 10 07 00 0f 84 e1 00 00 00 80 cc 40 89 c1 81 e1 ff ff ff fd 41 89 4d 00 49 8b 4d 60 <48> 81 39 10 21 4e 81 0f 84 66 01 00 00 83 43 04 01 41 83 45 04 01
All code
========
   0:	c1 00 00             	roll   $0x0,(%rax)
   3:	00 08                	add    %cl,(%rax)
   5:	0f 84 ed 00 00 00    	je     0xf8
   b:	81 e1 3f 10 07 00    	and    $0x7103f,%ecx
  11:	0f 84 e1 00 00 00    	je     0xf8
  17:	80 cc 40             	or     $0x40,%ah
  1a:	89 c1                	mov    %eax,%ecx
  1c:	81 e1 ff ff ff fd    	and    $0xfdffffff,%ecx
  22:	41 89 4d 00          	mov    %ecx,0x0(%r13)
  26:	49 8b 4d 60          	mov    0x60(%r13),%rcx
  2a:*	48 81 39 10 21 4e 81 	cmpq   $0xffffffff814e2110,(%rcx)		<-- trapping instruction
  31:	0f 84 66 01 00 00    	je     0x19d
  37:	83 43 04 01          	addl   $0x1,0x4(%rbx)
  3b:	41 83 45 04 01       	addl   $0x1,0x4(%r13)

Code starting with the faulting instruction
===========================================
   0:	48 81 39 10 21 4e 81 	cmpq   $0xffffffff814e2110,(%rcx)
   7:	0f 84 66 01 00 00    	je     0x173
   d:	83 43 04 01          	addl   $0x1,0x4(%rbx)
  11:	41 83 45 04 01       	addl   $0x1,0x4(%r13)


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20240118/202401181648.4192e541-oliver.sang@intel.com
Gabriel Krisman Bertazi Jan. 18, 2024, 6:58 p.m. UTC | #2 
kernel test robot <oliver.sang@intel.com> writes:

> Hello,
>
> kernel test robot noticed "BUG:kernel_NULL_pointer_dereference,address" on:
>
> commit: 1cfe4ba685d9eb6123648a0d9bef2d3d57b078ef ("[PATCH v3 04/10] fscrypt: Drop d_revalidate once the key is added")
> url: https://github.com/intel-lab-lkp/linux/commits/Gabriel-Krisman-Bertazi/ovl-Reject-mounting-case-insensitive-filesystems/20240112-070113
> base: https://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs.git dev-test
> patch link: https://lore.kernel.org/all/20240111225816.18117-5-krisman@suse.de/
> patch subject: [PATCH v3 04/10] fscrypt: Drop d_revalidate once the key is added
>
> in testcase: fxmark
> version: fxmark-x86_64-0ce9491-1_20220601
> with following parameters:
>
> 	disk: 1SSD
> 	media: ssd
> 	test: MWRL
> 	fstype: xfs
> 	directio: bufferedio
> 	cpufreq_governor: performance
>
>
>
> compiler: gcc-12
> test machine: 128 threads 2 sockets Intel(R) Xeon(R) Platinum 8358 CPU @ 2.60GHz (Ice Lake) with 128G memory
>
> (please refer to attached dmesg/kmsg for entire log/backtrace)
>
>
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@intel.com>
> | Closes: https://lore.kernel.org/oe-lkp/202401181648.4192e541-oliver.sang@intel.com
>
>
> [   73.173380][ T6828] BUG: kernel NULL pointer dereference, address: 0000000000000000
> [   73.181338][ T6828] #PF: supervisor read access in kernel mode
> [   73.187453][ T6828] #PF: error_code(0x0000) - not-present page
> [   73.193566][ T6828] PGD 11cc47067 P4D 0
> [   73.197762][ T6828] Oops: 0000 [#1] SMP NOPTI
> [   73.202383][ T6828] CPU: 16 PID: 6828 Comm: fxmark Tainted: G S                 6.7.0-rc1-00176-g1cfe4ba685d9 #1
> [   73.212818][ T6828] Hardware name: Intel Corporation M50CYP2SB1U/M50CYP2SB1U, BIOS SE5C620.86B.01.01.0003.2104260124 04/26/2021
> [ 73.224837][ T6828] RIP: 0010:__d_move (include/linux/fscrypt.h:241 fs/dcache.c:3003) 
> [ 73.229912][ T6828] Code: c1 00 00 00 08 0f 84 ed 00 00 00 81 e1 3f 10 07 00 0f 84 e1 00 00 00 80 cc 40 89 c1 81 e1 ff ff ff fd 41 89 4d 00 49 8b 4d 60 <48> 81 39 10 21 4e 81 0f 84 66 01 00 00 83 43 04 01 41 83 45 04 01
> All code
> ========
>    0:	c1 00 00             	roll   $0x0,(%rax)
>    3:	00 08                	add    %cl,(%rax)
>    5:	0f 84 ed 00 00 00    	je     0xf8
>    b:	81 e1 3f 10 07 00    	and    $0x7103f,%ecx
>   11:	0f 84 e1 00 00 00    	je     0xf8
>   17:	80 cc 40             	or     $0x40,%ah
>   1a:	89 c1                	mov    %eax,%ecx
>   1c:	81 e1 ff ff ff fd    	and    $0xfdffffff,%ecx
>   22:	41 89 4d 00          	mov    %ecx,0x0(%r13)
>   26:	49 8b 4d 60          	mov    0x60(%r13),%rcx
>   2a:*	48 81 39 10 21 4e 81 	cmpq   $0xffffffff814e2110,(%rcx)		<-- trapping instruction
>   31:	0f 84 66 01 00 00    	je     0x19d
>   37:	83 43 04 01          	addl   $0x1,0x4(%rbx)
>   3b:	41 83 45 04 01       	addl   $0x1,0x4(%r13)
>
> Code starting with the faulting instruction
> ===========================================
>    0:	48 81 39 10 21 4e 81 	cmpq   $0xffffffff814e2110,(%rcx)
>    7:	0f 84 66 01 00 00    	je     0x173
>    d:	83 43 04 01          	addl   $0x1,0x4(%rbx)
>   11:	41 83 45 04 01       	addl   $0x1,0x4(%r13)
> [   73.249920][ T6828] RSP: 0018:ffa000000a99bce8 EFLAGS: 00010206
> [   73.256134][ T6828] RAX: 0000000000480000 RBX: ff1100012cab5380 RCX: 0000000000000000
> [   73.264248][ T6828] RDX: ff1100012cab4609 RSI: 0000000000000000 RDI: ff1100012cab4600
> [   73.272366][ T6828] RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000020c
> [   73.280473][ T6828] R10: ff110001622ddde0 R11: 0000000000010000 R12: 0000000000000000
> [   73.288584][ T6828] R13: ff1100012cab4600 R14: 0000000000000000 R15: ff1100012cab5200
> [   73.296699][ T6828] FS:  00007f1073011600(0000) GS:ff1100103f600000(0000) knlGS:0000000000000000
> [   73.305766][ T6828] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   73.312488][ T6828] CR2: 0000000000000000 CR3: 000000012af2a006 CR4: 0000000000771ef0
> [   73.320596][ T6828] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [   73.328699][ T6828] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [   73.336803][ T6828] PKRU: 55555554
> [   73.340485][ T6828] Call Trace:
> [   73.343900][ T6828]  <TASK>
> [ 73.346960][ T6828] ? __die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434) 
> [ 73.350983][ T6828] ? page_fault_oops (arch/x86/mm/fault.c:707) 
> [ 73.355957][ T6828] ? exc_page_fault (arch/x86/include/asm/irqflags.h:37 arch/x86/include/asm/irqflags.h:72 arch/x86/mm/fault.c:1513 arch/x86/mm/fault.c:1561) 
> [ 73.360837][ T6828] ? asm_exc_page_fault (arch/x86/include/asm/idtentry.h:570) 
> [ 73.365974][ T6828] ? __d_move (include/linux/fscrypt.h:241 fs/dcache.c:3003) 
> [ 73.370410][ T6828] ? __d_move (arch/x86/include/asm/atomic.h:23 include/linux/atomic/atomic-arch-fallback.h:457 include/linux/atomic/atomic-instrumented.h:33 include/asm-generic/qspinlock.h:57 include/linux/fsnotify_backend.h:580 fs/dcache.c:3002) 
> [ 73.374846][ T6828] d_move (include/linux/seqlock.h:500 include/linux/seqlock.h:572 include/linux/seqlock.h:910 fs/dcache.c:3032) 
> [ 73.378757][ T6828] vfs_rename (include/linux/fs.h:807 fs/namei.c:4864) 
> [ 73.383189][ T6828] ? do_renameat2 (fs/namei.c:4996) 
> [ 73.387963][ T6828] do_renameat2 (fs/namei.c:4996) 
> [ 73.392568][ T6828] __x64_sys_rename (fs/namei.c:5040) 
> [ 73.397336][ T6828] do_syscall_64 (arch/x86/entry/common.c:51 arch/x86/entry/common.c:82) 
> [ 73.401835][ T6828] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:129) 
> [   73.407817][ T6828] RIP: 0033:0x7f1072e83ed7
> [ 73.412325][ T6828] Code: e8 6e 82 09 00 85 c0 0f 95 c0 0f b6 c0 f7 d8 5d c3 66 90 b8 ff ff ff ff 5d c3 66 0f 1f 84 00 00 00 00 00 b8 52 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 89 8f 17 00 f7 d8 64 89 02 b8
> All code
> ========
>    0:	e8 6e 82 09 00       	callq  0x98273
>    5:	85 c0                	test   %eax,%eax
>    7:	0f 95 c0             	setne  %al
>    a:	0f b6 c0             	movzbl %al,%eax
>    d:	f7 d8                	neg    %eax
>    f:	5d                   	pop    %rbp
>   10:	c3                   	retq   
>   11:	66 90                	xchg   %ax,%ax
>   13:	b8 ff ff ff ff       	mov    $0xffffffff,%eax
>   18:	5d                   	pop    %rbp
>   19:	c3                   	retq   
>   1a:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
>   21:	00 00 
>   23:	b8 52 00 00 00       	mov    $0x52,%eax
>   28:	0f 05                	syscall 
>   2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
>   30:	77 01                	ja     0x33
>   32:	c3                   	retq
>   33:	48 8b 15 89 8f 17 00 	mov    0x178f89(%rip),%rdx        # 0x178fc3
>   3a:	f7 d8                	neg    %eax
>   3c:	64 89 02             	mov    %eax,%fs:(%rdx)
>   3f:	b8                   	.byte 0xb8
>

Hm. So, the thing I missed here is that fscrypt_handle_d_move will be
called even by filesystems that don't support fscrypt.  While we know
fscrypt filesystem dentries must have ->d_op, others might not have
it, and the dereferencing of dentry->d_op causes the oops at:

  if (dentry->d_op->d_revalidate == fscrypt_d_revalidate)

causes the Oops.

One fix would be to prevent non-fscrypt filesystems from calling this
function. But since __d_move only touches the dentries, I think I'll
leave it as-is and just do:

  if (dentry->d_op && dentry->d_op->d_revalidate)

sorry for the noise.
diff mbox series

Patch

diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 3801c5c94fb6..379b423802fa 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -192,6 +192,8 @@  struct fscrypt_operations {
 					     unsigned int *num_devs);
 };
 
+int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags);
+
 static inline struct fscrypt_inode_info *
 fscrypt_get_inode_info(const struct inode *inode)
 {
@@ -230,6 +232,14 @@  static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
 static inline void fscrypt_handle_d_move(struct dentry *dentry)
 {
 	dentry->d_flags &= ~DCACHE_NOKEY_NAME;
+
+	/*
+	 * Save the d_revalidate call cost during VFS operations.  We
+	 * can do it because, when the key is available, the dentry
+	 * can't go stale and the key won't go away without eviction.
+	 */
+	if (dentry->d_op->d_revalidate == fscrypt_d_revalidate)
+		dentry->d_flags &= ~DCACHE_OP_REVALIDATE;
 }
 
 /**
@@ -368,7 +378,6 @@  int fscrypt_fname_disk_to_usr(const struct inode *inode,
 bool fscrypt_match_name(const struct fscrypt_name *fname,
 			const u8 *de_name, u32 de_name_len);
 u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name);
-int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags);
 
 /* bio.c */
 bool fscrypt_decrypt_bio(struct bio *bio);