| Message ID | 20220714091337.412297-1-rppt@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] secretmem: fix unhandled fault in truncate | expand |
On Thu 14-07-22 12:13:37, Mike Rapoport wrote: > From: Mike Rapoport <rppt@linux.ibm.com> > > syzkaller reports the following issue: > > BUG: unable to handle page fault for address: ffff888021f7e005 > PGD 11401067 P4D 11401067 PUD 11402067 PMD 21f7d063 PTE 800fffffde081060 > Oops: 0002 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 3761 Comm: syz-executor281 Not tainted 5.19.0-rc4-syzkaller-00014-g941e3e791269 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:64 > Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 > RSP: 0018:ffffc9000329fa90 EFLAGS: 00010202 > RAX: 0000000000000000 RBX: 0000000000001000 RCX: 0000000000000ffb > RDX: 0000000000000ffb RSI: 0000000000000000 RDI: ffff888021f7e005 > RBP: ffffea000087df80 R08: 0000000000000001 R09: ffff888021f7e005 > R10: ffffed10043efdff R11: 0000000000000000 R12: 0000000000000005 > R13: 0000000000000000 R14: 0000000000001000 R15: 0000000000000ffb > FS: 00007fb29d8b2700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffff888021f7e005 CR3: 0000000026e7b000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > zero_user_segments include/linux/highmem.h:272 [inline] > folio_zero_range include/linux/highmem.h:428 [inline] > truncate_inode_partial_folio+0x76a/0xdf0 mm/truncate.c:237 > truncate_inode_pages_range+0x83b/0x1530 mm/truncate.c:381 > truncate_inode_pages mm/truncate.c:452 [inline] > truncate_pagecache+0x63/0x90 mm/truncate.c:753 > simple_setattr+0xed/0x110 fs/libfs.c:535 > secretmem_setattr+0xae/0xf0 mm/secretmem.c:170 > notify_change+0xb8c/0x12b0 fs/attr.c:424 > do_truncate+0x13c/0x200 fs/open.c:65 > do_sys_ftruncate+0x536/0x730 fs/open.c:193 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > RIP: 0033:0x7fb29d900899 > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fb29d8b2318 EFLAGS: 00000246 ORIG_RAX: 000000000000004d > RAX: ffffffffffffffda RBX: 00007fb29d988408 RCX: 00007fb29d900899 > RDX: 00007fb29d900899 RSI: 0000000000000005 RDI: 0000000000000003 > RBP: 00007fb29d988400 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb29d98840c > R13: 00007ffca01a23bf R14: 00007fb29d8b2400 R15: 0000000000022000 > </TASK> > Modules linked in: > CR2: ffff888021f7e005 > ---[ end trace 0000000000000000 ]--- > > Eric Biggers suggested that this happens when > secretmem_setattr()->simple_setattr() races with secretmem_fault() so > that a page that is faulted in by secretmem_fault() (and thus removed > from the direct map) is zeroed by inode truncation right afterwards. > > Use an mapping->invalidate_lock to make secretmem_fault() and > secretmem_setattr() mutually exclusive. > > Reported-by: syzbot+9bd2b7adbd34b30b87e4@syzkaller.appspotmail.com > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> > Suggested-by: Eric Biggers <ebiggers@kernel.org> > Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Looks good to me. Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > v3: use invalidate_lock rather than inode_lock > v2: use inode_lock_shared() rather than add a new rw_sem to secretmem > > mm/secretmem.c | 33 ++++++++++++++++++++++++++------- > 1 file changed, 26 insertions(+), 7 deletions(-) > > diff --git a/mm/secretmem.c b/mm/secretmem.c > index 206ed6b40c1d..f06279d6190a 100644 > --- a/mm/secretmem.c > +++ b/mm/secretmem.c > @@ -55,22 +55,28 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) > gfp_t gfp = vmf->gfp_mask; > unsigned long addr; > struct page *page; > + vm_fault_t ret; > int err; > > if (((loff_t)vmf->pgoff << PAGE_SHIFT) >= i_size_read(inode)) > return vmf_error(-EINVAL); > > + filemap_invalidate_lock_shared(mapping); > + > retry: > page = find_lock_page(mapping, offset); > if (!page) { > page = alloc_page(gfp | __GFP_ZERO); > - if (!page) > - return VM_FAULT_OOM; > + if (!page) { > + ret = VM_FAULT_OOM; > + goto out; > + } > > err = set_direct_map_invalid_noflush(page); > if (err) { > put_page(page); > - return vmf_error(err); > + ret = vmf_error(err); > + goto out; > } > > __SetPageUptodate(page); > @@ -86,7 +92,8 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) > if (err == -EEXIST) > goto retry; > > - return vmf_error(err); > + ret = vmf_error(err); > + goto out; > } > > addr = (unsigned long)page_address(page); > @@ -94,7 +101,11 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) > } > > vmf->page = page; > - return VM_FAULT_LOCKED; > + ret = VM_FAULT_LOCKED; > + > +out: > + filemap_invalidate_unlock_shared(mapping); > + return ret; > } > > static const struct vm_operations_struct secretmem_vm_ops = { > @@ -162,12 +173,20 @@ static int secretmem_setattr(struct user_namespace *mnt_userns, > struct dentry *dentry, struct iattr *iattr) > { > struct inode *inode = d_inode(dentry); > + struct address_space *mapping = inode->i_mapping; > unsigned int ia_valid = iattr->ia_valid; > + int ret; > + > + filemap_invalidate_lock(mapping); > > if ((ia_valid & ATTR_SIZE) && inode->i_size) > - return -EINVAL; > + ret = -EINVAL; > + else > + ret = simple_setattr(mnt_userns, dentry, iattr); > > - return simple_setattr(mnt_userns, dentry, iattr); > + filemap_invalidate_unlock(mapping); > + > + return ret; > } > > static const struct inode_operations secretmem_iops = { > > base-commit: 03c765b0e3b4cb5063276b086c76f7a612856a9a > -- > 2.34.1 >
diff --git a/mm/secretmem.c b/mm/secretmem.c index 206ed6b40c1d..f06279d6190a 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -55,22 +55,28 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) gfp_t gfp = vmf->gfp_mask; unsigned long addr; struct page *page; + vm_fault_t ret; int err; if (((loff_t)vmf->pgoff << PAGE_SHIFT) >= i_size_read(inode)) return vmf_error(-EINVAL); + filemap_invalidate_lock_shared(mapping); + retry: page = find_lock_page(mapping, offset); if (!page) { page = alloc_page(gfp | __GFP_ZERO); - if (!page) - return VM_FAULT_OOM; + if (!page) { + ret = VM_FAULT_OOM; + goto out; + } err = set_direct_map_invalid_noflush(page); if (err) { put_page(page); - return vmf_error(err); + ret = vmf_error(err); + goto out; } __SetPageUptodate(page); @@ -86,7 +92,8 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) if (err == -EEXIST) goto retry; - return vmf_error(err); + ret = vmf_error(err); + goto out; } addr = (unsigned long)page_address(page); @@ -94,7 +101,11 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) } vmf->page = page; - return VM_FAULT_LOCKED; + ret = VM_FAULT_LOCKED; + +out: + filemap_invalidate_unlock_shared(mapping); + return ret; } static const struct vm_operations_struct secretmem_vm_ops = { @@ -162,12 +173,20 @@ static int secretmem_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, struct iattr *iattr) { struct inode *inode = d_inode(dentry); + struct address_space *mapping = inode->i_mapping; unsigned int ia_valid = iattr->ia_valid; + int ret; + + filemap_invalidate_lock(mapping); if ((ia_valid & ATTR_SIZE) && inode->i_size) - return -EINVAL; + ret = -EINVAL; + else + ret = simple_setattr(mnt_userns, dentry, iattr); - return simple_setattr(mnt_userns, dentry, iattr); + filemap_invalidate_unlock(mapping); + + return ret; } static const struct inode_operations secretmem_iops = {