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[128.101.106.63]) by smtp.gmail.com with ESMTPSA id c1sm792474itd.23.2019.03.14.00.46.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 14 Mar 2019 00:46:12 -0700 (PDT) From: Kangjie Lu To: kjlu@umn.edu Cc: pakki001@umn.edu, David Sterba , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] fs: affs: fix a NULL pointer dereference Date: Thu, 14 Mar 2019 02:46:05 -0500 Message-Id: <20190314074607.28041-1-kjlu@umn.edu> X-Mailer: git-send-email 2.17.1 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org If affs_bread fails, do not use ext_bh to avoid NULL pointer dereference Signed-off-by: Kangjie Lu --- fs/affs/file.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/affs/file.c b/fs/affs/file.c index a85817f54483..45b96faa40f1 100644 --- a/fs/affs/file.c +++ b/fs/affs/file.c @@ -835,7 +835,7 @@ void affs_truncate(struct inode *inode) { struct super_block *sb = inode->i_sb; - u32 ext, ext_key; + u32 ext, ext_key, ext_bk; u32 last_blk, blkcnt, blk; u32 size; struct buffer_head *ext_bh; @@ -941,8 +941,12 @@ affs_truncate(struct inode *inode) size = AFFS_SB(sb)->s_hashsize; if (size > blkcnt - blk) size = blkcnt - blk; - for (i = 0; i < size; i++, blk++) - affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i))); + if (ext_bh) { + for (i = 0; i < size; i++, blk++) { + ext_bk = AFFS_BLOCK(sb, ext_bh, i); + affs_free_block(sb, be32_to_cpu(ext_bk)); + } + } affs_free_block(sb, ext_key); ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension); affs_brelse(ext_bh); -- 2.17.1