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jfs: validate max amount of blocks before allocation. 

The lack of checking bmp->db_max_freebud in extBalloc() can lead to
shift out of bounds, so this patch prevents undefined behavior, because
bmp->db_max_freebud == -1 only if there is no free space.

Signed-off-by: Aleksei Filippov <halip0503@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-and-tested-by: syzbot+5f088f29593e6b4c8db8@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?id=01abadbd6ae6a08b1f1987aa61554c6b3ac19ff2
This commit is contained in:
Alexei Filippov 2023-08-19 20:32:16 +03:00 committed by Dave Kleikamp
parent 87098a0d9e
commit 0225e10972
1 changed files with 5 additions and 0 deletions
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5
fs/jfs/jfs_extent.c
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@ -311,6 +311,11 @@ extBalloc(struct inode *ip, s64 hint, s64 * nblocks, s64 * blkno)
* blocks in the map. in that case, we'll start off with the
* maximum free.
*/
/* give up if no space left */
if (bmp->db_maxfreebud == -1)
return -ENOSPC;
max = (s64) 1 << bmp->db_maxfreebud;
if (*nblocks >= max && *nblocks > nbperpage)
nb = nblks = (max > nbperpage) ? max : nbperpage;