4.14-stable review patch. If anyone has any objections, please let me know.
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From: Alexei Filippov halip0503@gmail.com
[ Upstream commit 0225e10972fa809728b8d4c1bd2772b3ec3fdb57 ]
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: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-and-tested-by: syzbot+5f088f29593e6b4c8db8@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?id=01abadbd6ae6a08b1f1987aa61554c6b3ac19ff... Signed-off-by: Sasha Levin sashal@kernel.org --- fs/jfs/jfs_extent.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/fs/jfs/jfs_extent.c b/fs/jfs/jfs_extent.c index 2ae7d59ab10a5..c971e8a6525de 100644 --- a/fs/jfs/jfs_extent.c +++ b/fs/jfs/jfs_extent.c @@ -521,6 +521,11 @@ 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;