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Date: Fri, 1 May 2020 11:59:54 +0530 From: Ritesh Harjani <riteshh@...ux.ibm.com> To: linux-ext4@...r.kernel.org Cc: "Paul E . McKenney" <paulmck@...nel.org>, linux-fsdevel@...r.kernel.org, Jan Kara <jack@...e.com>, tytso@....edu, "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>, Ritesh Harjani <riteshh@...ux.ibm.com> Subject: [RFC 12/20] ext4: mballoc: Fix possible NULL ptr dereference from mb_cmp_bitmaps() Make sure to check for e4b->bd_info->bb_bitmap == NULL, in mb_cmp_bitmaps() and return if NULL, to avoid possible NULL ptr dereference. Similar to how we do this in other ifdef DOUBLE_CHECK functions. Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com> --- fs/ext4/mballoc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 5e59c18c89c0..e32f3675f962 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -522,6 +522,8 @@ static void mb_mark_used_double(struct ext4_buddy *e4b, int first, int count) static void mb_cmp_bitmaps(struct ext4_buddy *e4b, void *bitmap) { + if (unlikely(e4b->bd_info->bb_bitmap == NULL)) + return; if (memcmp(e4b->bd_info->bb_bitmap, bitmap, e4b->bd_sb->s_blocksize)) { unsigned char *b1, *b2; int i; -- 2.21.0
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