kernel.git/fs/udf/inode.c, branch linux-5.4.y

fs: udf: fix OOB read in lengthAllocDescs handling

2025-10-29T12:59:54Z

[ Upstream commit 3bd5e45c2ce30e239d596becd5db720f7eb83c99 ] When parsing Allocation Extent Descriptor, lengthAllocDescs comes from on-disk data and must be validated against the block size. Crafted or corrupted images may set lengthAllocDescs so that the total descriptor length (sizeof(allocExtDesc) + lengthAllocDescs) exceeds the buffer, leading udf_update_tag() to call crc_itu_t() on out-of-bounds memory and trigger a KASAN use-after-free read. BUG: KASAN: use-after-free in crc_itu_t+0x1d5/0x2b0 lib/crc-itu-t.c:60 Read of size 1 at addr ffff888041e7d000 by task syz-executor317/5309 CPU: 0 UID: 0 PID: 5309 Comm: syz-executor317 Not tainted 6.12.0-rc4-syzkaller-00261-g850925a8133c #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 crc_itu_t+0x1d5/0x2b0 lib/crc-itu-t.c:60 udf_update_tag+0x70/0x6a0 fs/udf/misc.c:261 udf_write_aext+0x4d8/0x7b0 fs/udf/inode.c:2179 extent_trunc+0x2f7/0x4a0 fs/udf/truncate.c:46 udf_truncate_tail_extent+0x527/0x7e0 fs/udf/truncate.c:106 udf_release_file+0xc1/0x120 fs/udf/file.c:185 __fput+0x23f/0x880 fs/file_table.c:431 task_work_run+0x24f/0x310 kernel/task_work.c:239 exit_task_work include/linux/task_work.h:43 [inline] do_exit+0xa2f/0x28e0 kernel/exit.c:939 do_group_exit+0x207/0x2c0 kernel/exit.c:1088 __do_sys_exit_group kernel/exit.c:1099 [inline] __se_sys_exit_group kernel/exit.c:1097 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Validate the computed total length against epos->bh->b_size. Found by Linux Verification Center (linuxtesting.org) with Syzkaller. Reported-by: syzbot+8743fca924afed42f93e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=8743fca924afed42f93e Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Larshin Sergey Link: https://patch.msgid.link/20250922131358.745579-1-Sergey.Larshin@kaspersky.com Signed-off-by: Jan Kara Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

udf: fix uninit-value use in udf_get_fileshortad

2024-11-08T15:20:50Z

[ Upstream commit 264db9d666ad9a35075cc9ed9ec09d021580fbb1 ] Check for overflow when computing alen in udf_current_aext to mitigate later uninit-value use in udf_get_fileshortad KMSAN bug[1]. After applying the patch reproducer did not trigger any issue[2]. [1] https://syzkaller.appspot.com/bug?extid=8901c4560b7ab5c2f9df [2] https://syzkaller.appspot.com/x/log.txt?x=10242227980000 Reported-by: syzbot+8901c4560b7ab5c2f9df@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=8901c4560b7ab5c2f9df Tested-by: syzbot+8901c4560b7ab5c2f9df@syzkaller.appspotmail.com Suggested-by: Jan Kara Signed-off-by: Gianfranco Trad Signed-off-by: Jan Kara Link: https://patch.msgid.link/20240925074613.8475-3-gianf.trad@gmail.com Signed-off-by: Sasha Levin

udf: initialize newblock to 0

2023-09-23T08:59:56Z

commit 23970a1c9475b305770fd37bebfec7a10f263787 upstream. The clang build reports this error fs/udf/inode.c:805:6: error: variable 'newblock' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] if (*err < 0) ^~~~~~~~ newblock is never set before error handling jump. Initialize newblock to 0 and remove redundant settings. Fixes: d8b39db5fab8 ("udf: Handle error when adding extent to a file") Reported-by: Nathan Chancellor Signed-off-by: Tom Rix Signed-off-by: Jan Kara Message-Id: <20221230175341.1629734-1-trix@redhat.com> Signed-off-by: Greg Kroah-Hartman

udf: Handle error when adding extent to a file

2023-09-23T08:59:40Z

commit 19fd80de0a8b5170ef34704c8984cca920dffa59 upstream. When adding extent to a file fails, so far we've silently squelshed the error. Make sure to propagate it up properly. Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

udf: Fix file corruption when appending just after end of preallocated extent

2023-03-11T15:44:01Z

commit 36ec52ea038b18a53e198116ef7d7e70c87db046 upstream. When we append new block just after the end of preallocated extent, the code in inode_getblk() wrongly determined we're going to use the preallocated extent which resulted in adding block into a wrong logical offset in the file. Sequence like this manifests it: xfs_io -f -c "pwrite 0x2cacf 0xd122" -c "truncate 0x2dd6f" \ -c "pwrite 0x27fd9 0x69a9" -c "pwrite 0x32981 0x7244" The code that determined the use of preallocated extent is actually stale because udf_do_extend_file() does not create preallocation anymore so after calling that function we are sure there's no usable preallocation. Just remove the faulty condition. CC: stable@vger.kernel.org Fixes: 16d055656814 ("udf: Discard preallocation before extending file with a hole") Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

udf: Detect system inodes linked into directory hierarchy

2023-03-11T15:44:00Z

commit 85a37983ec69cc9fcd188bc37c4de15ee326355a upstream. When UDF filesystem is corrupted, hidden system inodes can be linked into directory hierarchy which is an avenue for further serious corruption of the filesystem and kernel confusion as noticed by syzbot fuzzed images. Refuse to access system inodes linked into directory hierarchy and vice versa. CC: stable@vger.kernel.org Reported-by: syzbot+38695a20b8addcbc1084@syzkaller.appspotmail.com Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

udf: Preserve link count of system files

2023-03-11T15:44:00Z

commit fc8033a34a3ca7d23353e645e6dde5d364ac5f12 upstream. System files in UDF filesystem have link count 0. To not confuse VFS we fudge the link count to be 1 when reading such inodes however we forget to restore the link count of 0 when writing such inodes. Fix that. CC: stable@vger.kernel.org Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

udf: Do not bother merging very long extents

2023-03-11T15:44:00Z

commit 53cafe1d6d8ef9f93318e5bfccc0d24f27d41ced upstream. When merging very long extents we try to push as much length as possible to the first extent. However this is unnecessarily complicated and not really worth the trouble. Furthermore there was a bug in the logic resulting in corrupting extents in the file as syzbot reproducer shows. So just don't bother with the merging of extents that are too long together. CC: stable@vger.kernel.org Reported-by: syzbot+60f291a24acecb3c2bd5@syzkaller.appspotmail.com Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

udf: Truncate added extents on failed expansion

2023-03-11T15:44:00Z

commit 70bfb3a8d661d4fdc742afc061b88a7f3fc9f500 upstream. When a file expansion failed because we didn't have enough space for indirect extents make sure we truncate extents created so far so that we don't leave extents beyond EOF. CC: stable@vger.kernel.org Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

udf: Fix extension of the last extent in the file

2023-01-18T10:41:58Z

[ Upstream commit 83c7423d1eb6806d13c521d1002cc1a012111719 ] When extending the last extent in the file within the last block, we wrongly computed the length of the last extent. This is mostly a cosmetical problem since the extent does not contain any data and the length will be fixed up by following operations but still. Fixes: 1f3868f06855 ("udf: Fix extending file within last block") Signed-off-by: Jan Kara Signed-off-by: Sasha Levin