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| author | Theodore Ts'o <tytso@mit.edu> | 2023-04-29 23:14:46 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-17 12:50:30 +0300 |
| commit | 978e5e9111af18741449b81fefd531a622dd969a (patch) | |
| tree | 5fb777399dd370a7ff881b44ea4b6121775c4164 | |
| parent | 2b3b8f18c0dc10bce6e5792f24df882d030fa511 (diff) | |
| download | linux-978e5e9111af18741449b81fefd531a622dd969a.tar.xz | |
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>
| -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 e6718bfc6c55..0e0226b30db6 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4832,7 +4832,11 @@ 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); |