[PATCH] erofs: fix shift-out-of-bounds of blkszbits

From: Gao Xiang
Date: Tue Jan 19 2021 - 20:43:13 EST


From: Gao Xiang <hsiangkao@xxxxxxxxxx>

syzbot generated a crafted bitszbits which can be shifted
out-of-bounds[1]. So directly print unsupported blkszbits
instead of blksize.

[1] https://lore.kernel.org/r/000000000000c72ddd05b9444d2f@xxxxxxxxxx
Reported-by: syzbot+c68f467cd7c45860e8d4@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
---
fs/erofs/super.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index be10b16ea66e..d5a6b9b888a5 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -158,8 +158,8 @@ static int erofs_read_superblock(struct super_block *sb)
blkszbits = dsb->blkszbits;
/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
if (blkszbits != LOG_BLOCK_SIZE) {
- erofs_err(sb, "blksize %u isn't supported on this platform",
- 1 << blkszbits);
+ erofs_err(sb, "blkszbits %u isn't supported on this platform",
+ blkszbits);
goto out;
}

--
2.24.0