Commit 64beba05 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: sanity check of xattr entry size 



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: <stable@vger.kernel.org>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 60aa4d55

fs/f2fs/xattr.c

+13 −5
Original line number Diff line number Diff line
@@ -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;
@@ -312,9 +312,11 @@ 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 */

	if (xnid) {
@@ -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;

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