From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaegeuk Kim Subject: [PATCH] f2fs: sanity check of xattr entry size Date: Wed, 26 Dec 2018 20:04:24 -0800 Message-ID: <20181227040424.77190-1-jaegeuk@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1gcMuR-0003in-1z for linux-f2fs-devel@lists.sourceforge.net; Thu, 27 Dec 2018 04:04:35 +0000 Received: from mail.kernel.org ([198.145.29.99]) by sfi-mx-4.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1gcMuN-002DGk-Ju for linux-f2fs-devel@lists.sourceforge.net; Thu, 27 Dec 2018 04:04:35 +0000 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Cc: Jaegeuk Kim , stable@vger.kernel.org There is a security report where f2fs_getxattr() has a hole to expose wrong memory region when the image is malformed like this. f2fs_getxattr: entry->e_name_len: 4, size: 12288, buffer_size: 16384, len: 4 Cc: Signed-off-by: Jaegeuk Kim --- fs/f2fs/xattr.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c index f44b0c38398b..18d5ffbc5e8c 100644 --- a/fs/f2fs/xattr.c +++ b/fs/f2fs/xattr.c @@ -288,7 +288,7 @@ static int read_xattr_block(struct inode *inode, void *txattr_addr) static int lookup_all_xattrs(struct inode *inode, struct page *ipage, unsigned int index, unsigned int len, const char *name, struct f2fs_xattr_entry **xe, - void **base_addr) + void **base_addr, int *base_size) { void *cur_addr, *txattr_addr, *last_addr = NULL; nid_t xnid = F2FS_I(inode)->i_xattr_nid; @@ -299,8 +299,8 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage, if (!size && !inline_size) return -ENODATA; - txattr_addr = f2fs_kzalloc(F2FS_I_SB(inode), - inline_size + size + XATTR_PADDING_SIZE, GFP_NOFS); + *base_size = inline_size + size + XATTR_PADDING_SIZE; + txattr_addr = f2fs_kzalloc(F2FS_I_SB(inode), *base_size, GFP_NOFS); if (!txattr_addr) return -ENOMEM; @@ -312,8 +312,10 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage, *xe = __find_inline_xattr(inode, txattr_addr, &last_addr, index, len, name); - if (*xe) + if (*xe) { + *base_size = inline_size; goto check; + } } /* read from xattr node block */ @@ -474,6 +476,7 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name, int error = 0; unsigned int size, len; void *base_addr = NULL; + int base_size; if (name == NULL) return -EINVAL; @@ -484,7 +487,7 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name, down_read(&F2FS_I(inode)->i_xattr_sem); error = lookup_all_xattrs(inode, ipage, index, len, name, - &entry, &base_addr); + &entry, &base_addr, &base_size); up_read(&F2FS_I(inode)->i_xattr_sem); if (error) return error; @@ -498,6 +501,11 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name, if (buffer) { char *pval = entry->e_name + entry->e_name_len; + + if (base_size - (pval - (char *)base_addr) < size) { + error = -ERANGE; + goto out; + } memcpy(buffer, pval, size); } error = size; -- 2.19.0.605.g01d371f741-goog