From: Jaegeuk Kim <[email protected]> commit 64beba0558fce7b59e9a8a7afd77290e82a22163 upstream.
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 Signed-off-by: Jaegeuk Kim <[email protected]> [bwh: Backported to 4.14: Keep using kzalloc()] Signed-off-by: Ben Hutchings <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/f2fs/xattr.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) --- a/fs/f2fs/xattr.c +++ b/fs/f2fs/xattr.c @@ -287,7 +287,7 @@ static int read_xattr_block(struct inode 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; @@ -298,8 +298,8 @@ static int lookup_all_xattrs(struct inod if (!size && !inline_size) return -ENODATA; - txattr_addr = kzalloc(inline_size + size + XATTR_PADDING_SIZE, - GFP_F2FS_ZERO); + *base_size = inline_size + size + XATTR_PADDING_SIZE; + txattr_addr = kzalloc(*base_size, GFP_F2FS_ZERO); if (!txattr_addr) return -ENOMEM; @@ -311,8 +311,10 @@ static int lookup_all_xattrs(struct inod *xe = __find_inline_xattr(txattr_addr, &last_addr, index, len, name); - if (*xe) + if (*xe) { + *base_size = inline_size; goto check; + } } /* read from xattr node block */ @@ -462,6 +464,7 @@ int f2fs_getxattr(struct inode *inode, i int error = 0; unsigned int size, len; void *base_addr = NULL; + int base_size; if (name == NULL) return -EINVAL; @@ -472,7 +475,7 @@ int f2fs_getxattr(struct inode *inode, i 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; @@ -486,6 +489,11 @@ int f2fs_getxattr(struct inode *inode, i 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;
