diff options
| author | Theodore Ts'o | 2023-04-29 16:14:46 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2023-05-17 11:53:58 +0200 |
| commit | d87a4e4094c9879fc8acdff8ce59fdffa979c8e0 (patch) | |
| tree | 771ab2747480185575d9c0db70e526a322fdc06a /fs | |
| parent | 19fb73b8eaefccc48918c2f915d021bd4a5572a7 (diff) | |
ext4: remove a BUG_ON in ext4_mb_release_group_pa()
commit 463808f237cf73e98a1a45ff7460c2406a150a0b upstream.
If a malicious fuzzer overwrites the ext4 superblock while it is
mounted such that the s_first_data_block is set to a very large
number, the calculation of the block group can underflow, and trigger
a BUG_ON check. Change this to be an ext4_warning so that we don't
crash the kernel.
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230430154311.579720-3-tytso@mit.edu
Reported-by: syzbot+e2efa3efc15a1c9e95c3@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=69b28112e098b070f639efb356393af3ffec4220
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/mballoc.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 9dad93059945..912c4a1093fe 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4820,7 +4820,11 @@ ext4_mb_release_group_pa(struct ext4_buddy *e4b, trace_ext4_mb_release_group_pa(sb, pa); BUG_ON(pa->pa_deleted == 0); ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, &bit); - BUG_ON(group != e4b->bd_group && pa->pa_len != 0); + if (unlikely(group != e4b->bd_group && pa->pa_len != 0)) { + ext4_warning(sb, "bad group: expected %u, group %u, pa_start %llu", + e4b->bd_group, group, pa->pa_pstart); + return 0; + } mb_free_blocks(pa->pa_inode, e4b, bit, pa->pa_len); atomic_add(pa->pa_len, &EXT4_SB(sb)->s_mb_discarded); trace_ext4_mballoc_discard(sb, NULL, group, bit, pa->pa_len); |