| Message ID | 20241107114109.839253-1-cascardo@igalia.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | hfsplus: don't query the device logical block size multiple times | expand |
On Thu, 07 Nov 2024 08:41:09 -0300, Thadeu Lima de Souza Cascardo wrote: > Devices block sizes may change. One of these cases is a loop device by > using ioctl LOOP_SET_BLOCK_SIZE. > > While this may cause other issues like IO being rejected, in the case of > hfsplus, it will allocate a block by using that size and potentially write > out-of-bounds when hfsplus_read_wrapper calls hfsplus_submit_bio and the > latter function reads a different io_size. > > [...] Applied to the vfs.misc branch of the vfs/vfs.git tree. Patches in the vfs.misc branch should appear in linux-next soon. Please report any outstanding bugs that were missed during review in a new review to the original patch series allowing us to drop it. It's encouraged to provide Acked-bys and Reviewed-bys even though the patch has now been applied. If possible patch trailers will be updated. Note that commit hashes shown below are subject to change due to rebase, trailer updates or similar. If in doubt, please check the listed branch. tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git branch: vfs.misc [1/1] hfsplus: don't query the device logical block size multiple times https://git.kernel.org/vfs/vfs/c/b05565a8e3b8
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h index 59ce81dca73f..5389918bbf29 100644 --- a/fs/hfsplus/hfsplus_fs.h +++ b/fs/hfsplus/hfsplus_fs.h @@ -156,6 +156,7 @@ struct hfsplus_sb_info { /* Runtime variables */ u32 blockoffset; + u32 min_io_size; sector_t part_start; sector_t sect_count; int fs_shift; @@ -307,7 +308,7 @@ struct hfsplus_readdir_data { */ static inline unsigned short hfsplus_min_io_size(struct super_block *sb) { - return max_t(unsigned short, bdev_logical_block_size(sb->s_bdev), + return max_t(unsigned short, HFSPLUS_SB(sb)->min_io_size, HFSPLUS_SECTOR_SIZE); } diff --git a/fs/hfsplus/wrapper.c b/fs/hfsplus/wrapper.c index 9592ffcb44e5..74801911bc1c 100644 --- a/fs/hfsplus/wrapper.c +++ b/fs/hfsplus/wrapper.c @@ -172,6 +172,8 @@ int hfsplus_read_wrapper(struct super_block *sb) if (!blocksize) goto out; + sbi->min_io_size = blocksize; + if (hfsplus_get_last_session(sb, &part_start, &part_size)) goto out;
Devices block sizes may change. One of these cases is a loop device by using ioctl LOOP_SET_BLOCK_SIZE. While this may cause other issues like IO being rejected, in the case of hfsplus, it will allocate a block by using that size and potentially write out-of-bounds when hfsplus_read_wrapper calls hfsplus_submit_bio and the latter function reads a different io_size. Using a new min_io_size initally set to sb_min_blocksize works for the purposes of the original fix, since it will be set to the max between HFSPLUS_SECTOR_SIZE and the first seen logical block size. We still use the max between HFSPLUS_SECTOR_SIZE and min_io_size in case the latter is not initialized. Tested by mounting an hfsplus filesystem with loop block sizes 512, 1024 and 4096. The produced KASAN report before the fix looks like this: [ 419.944641] ================================================================== [ 419.945655] BUG: KASAN: slab-use-after-free in hfsplus_read_wrapper+0x659/0xa0a [ 419.946703] Read of size 2 at addr ffff88800721fc00 by task repro/10678 [ 419.947612] [ 419.947846] CPU: 0 UID: 0 PID: 10678 Comm: repro Not tainted 6.12.0-rc5-00008-gdf56e0f2f3ca #84 [ 419.949007] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 [ 419.950035] Call Trace: [ 419.950384] <TASK> [ 419.950676] dump_stack_lvl+0x57/0x78 [ 419.951212] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.951830] print_report+0x14c/0x49e [ 419.952361] ? __virt_addr_valid+0x267/0x278 [ 419.952979] ? kmem_cache_debug_flags+0xc/0x1d [ 419.953561] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.954231] kasan_report+0x89/0xb0 [ 419.954748] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.955367] hfsplus_read_wrapper+0x659/0xa0a [ 419.955948] ? __pfx_hfsplus_read_wrapper+0x10/0x10 [ 419.956618] ? do_raw_spin_unlock+0x59/0x1a9 [ 419.957214] ? _raw_spin_unlock+0x1a/0x2e [ 419.957772] hfsplus_fill_super+0x348/0x1590 [ 419.958355] ? hlock_class+0x4c/0x109 [ 419.958867] ? __pfx_hfsplus_fill_super+0x10/0x10 [ 419.959499] ? __pfx_string+0x10/0x10 [ 419.960006] ? lock_acquire+0x3e2/0x454 [ 419.960532] ? bdev_name.constprop.0+0xce/0x243 [ 419.961129] ? __pfx_bdev_name.constprop.0+0x10/0x10 [ 419.961799] ? pointer+0x3f0/0x62f [ 419.962277] ? __pfx_pointer+0x10/0x10 [ 419.962761] ? vsnprintf+0x6c4/0xfba [ 419.963178] ? __pfx_vsnprintf+0x10/0x10 [ 419.963621] ? setup_bdev_super+0x376/0x3b3 [ 419.964029] ? snprintf+0x9d/0xd2 [ 419.964344] ? __pfx_snprintf+0x10/0x10 [ 419.964675] ? lock_acquired+0x45c/0x5e9 [ 419.965016] ? set_blocksize+0x139/0x1c1 [ 419.965381] ? sb_set_blocksize+0x6d/0xae [ 419.965742] ? __pfx_hfsplus_fill_super+0x10/0x10 [ 419.966179] mount_bdev+0x12f/0x1bf [ 419.966512] ? __pfx_mount_bdev+0x10/0x10 [ 419.966886] ? vfs_parse_fs_string+0xce/0x111 [ 419.967293] ? __pfx_vfs_parse_fs_string+0x10/0x10 [ 419.967702] ? __pfx_hfsplus_mount+0x10/0x10 [ 419.968073] legacy_get_tree+0x104/0x178 [ 419.968414] vfs_get_tree+0x86/0x296 [ 419.968751] path_mount+0xba3/0xd0b [ 419.969157] ? __pfx_path_mount+0x10/0x10 [ 419.969594] ? kmem_cache_free+0x1e2/0x260 [ 419.970311] do_mount+0x99/0xe0 [ 419.970630] ? __pfx_do_mount+0x10/0x10 [ 419.971008] __do_sys_mount+0x199/0x1c9 [ 419.971397] do_syscall_64+0xd0/0x135 [ 419.971761] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 419.972233] RIP: 0033:0x7c3cb812972e [ 419.972564] Code: 48 8b 0d f5 46 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c2 46 0d 00 f7 d8 64 89 01 48 [ 419.974371] RSP: 002b:00007ffe30632548 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5 [ 419.975048] RAX: ffffffffffffffda RBX: 00007ffe306328d8 RCX: 00007c3cb812972e [ 419.975701] RDX: 0000000020000000 RSI: 0000000020000c80 RDI: 00007ffe306325d0 [ 419.976363] RBP: 00007ffe30632720 R08: 00007ffe30632610 R09: 0000000000000000 [ 419.977034] R10: 0000000000200008 R11: 0000000000000286 R12: 0000000000000000 [ 419.977713] R13: 00007ffe306328e8 R14: 00005a0eb298bc68 R15: 00007c3cb8356000 [ 419.978375] </TASK> [ 419.978589] Fixes: 6596528e391a ("hfsplus: ensure bio requests are not smaller than the hardware sectors") Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com> --- fs/hfsplus/hfsplus_fs.h | 3 ++- fs/hfsplus/wrapper.c | 2 ++ 2 files changed, 4 insertions(+), 1 deletion(-)