[PATCH v3 3/6] qnx6: avoid double brelse() on error path in qnx6_fill_super()

[Hui Peng <benquike@gmail.com>]

In qnx6_fill_super(), sb_buf is assigned the return value of
sb_bread(sb, 1). If parsing the primary superblock fails, execution
branches to out_sbl2, which calls brelse(sbi->sb_buf) and then falls
through to out_sbl1, which calls brelse(sb_buf) a second time on the same
buffer head pointer, causing a double free / refcount underflow.

Fix the error-handling cleanup sequence in qnx6_fill_super() to avoid
calling brelse(sb_buf) twice.

Fixes: 5d026c724220 ("fs: initial qnx6fs addition")
Cc: stable@vger.kernel.org
Tested-by: Matthias Goergens <matthias.goergens@gmail.com>
Reviewed-by: Matthias Goergens <matthias.goergens@gmail.com>
Assisted-by: LLM
Signed-off-by: Hui Peng <benquike@gmail.com>
---
Changes in v3:
- Add Tested-by and Reviewed-by tags from Matthias Goergens.
- Update Fixes: tag SHA to 5d026c724220 ("fs: initial qnx6fs addition").

Changes in v2:
- Split out as patch 3/6 as requested by maintainers.

 fs/qnx6/inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/qnx6/inode.c b/fs/qnx6/inode.c
index 444458ce3e77..70438cf5efdf 100644
--- a/fs/qnx6/inode.c
+++ b/fs/qnx6/inode.c
@@ -348,7 +348,7 @@ static int qnx6_fill_super(struct super_block *s, void *data, int silent)
 out_sbl2:
 	brelse(sbi->sb_buf);
 	sbi->sb_buf = NULL;
-out_sbl1:
+out_sbl1:
 	brelse(sb_buf);
 	return -EINVAL;
 }
-- 
2.55.0.1082.g2b9226bbc0-goog