linux-kernel - [PATCH 2/3] fs/ntfs3: Potential NULL dereference in hdr_find

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Message-ID: <20210824075015.GB13096@kili>
Date:   Tue, 24 Aug 2021 10:50:15 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
Cc:     ntfs3@...ts.linux.dev, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH 2/3] fs/ntfs3: Potential NULL dereference in hdr_find_split()

The "e" pointer is dereferenced before it has been checked for NULL.
Move the dereference after the NULL check to prevent an Oops.

Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 fs/ntfs3/index.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 07d6dee0a4ba..489e0fffbc75 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -556,11 +556,12 @@ static const struct NTFS_DE *hdr_find_split(const struct INDEX_HDR *hdr)
 	size_t o;
 	const struct NTFS_DE *e = hdr_first_de(hdr);
 	u32 used_2 = le32_to_cpu(hdr->used) >> 1;
-	u16 esize = le16_to_cpu(e->size);
+	u16 esize;
 
 	if (!e || de_is_last(e))
 		return NULL;
 
+	esize = le16_to_cpu(e->size);
 	for (o = le32_to_cpu(hdr->de_off) + esize; o < used_2; o += esize) {
 		const struct NTFS_DE *p = e;
 
-- 
2.20.1