From patchwork Wed Apr 25 18:45:22 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [v2, 1/2] jffs2: validate symlink size in jffs2_do_read_inode_internal() From: Xi Wang X-Patchwork-Id: 155057 Message-Id: <1335379523-31415-1-git-send-email-xi.wang@gmail.com> To: David Woodhouse Cc: linux-mtd@lists.infradead.org, Xi Wang , Artem Bityutskiy Date: Wed, 25 Apr 2012 14:45:22 -0400 `csize' is read from disk and thus needs validation. Otherwise a bogus value 0xffffffff would turn the subsequent kmalloc(csize + 1, ...) into kmalloc(0, ...), leading to out-of-bounds write. This patch limits `csize' to JFFS2_MAX_NAME_LEN, which is also used in jffs2_symlink(). Signed-off-by: Xi Wang Cc: Artem Bityutskiy --- fs/jffs2/readinode.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c index dc0437e..9897f38 100644 --- a/fs/jffs2/readinode.c +++ b/fs/jffs2/readinode.c @@ -1266,6 +1266,12 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c, /* Symlink's inode data is the target path. Read it and * keep in RAM to facilitate quick follow symlink * operation. */ + uint32_t csize = je32_to_cpu(latest_node->csize); + if (csize > JFFS2_MAX_NAME_LEN) { + mutex_unlock(&f->sem); + jffs2_do_clear_inode(c, f); + return -ENAMETOOLONG; + } f->target = kmalloc(je32_to_cpu(latest_node->csize) + 1, GFP_KERNEL); if (!f->target) { JFFS2_ERROR("can't allocate %d bytes of memory for the symlink target path cache\n", je32_to_cpu(latest_node->csize));