The kernel would like to have all stack VLA usage removed[1]. This switches to a simple kasprintf() instead, and in the process fixes an off-by-one between the allocation and the sprintf (allocation did not include NULL byte in calculation).
[1] https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Kees Cook <keesc...@chromium.org> Reviewed-by: Rasmus Villemoes <li...@rasmusvillemoes.dk> --- drivers/staging/lustre/lustre/llite/xattr.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/drivers/staging/lustre/lustre/llite/xattr.c b/drivers/staging/lustre/lustre/llite/xattr.c index 532384c91447..ff6fe81a4ddb 100644 --- a/drivers/staging/lustre/lustre/llite/xattr.c +++ b/drivers/staging/lustre/lustre/llite/xattr.c @@ -87,10 +87,10 @@ ll_xattr_set_common(const struct xattr_handler *handler, const char *name, const void *value, size_t size, int flags) { - char fullname[strlen(handler->prefix) + strlen(name) + 1]; struct ll_sb_info *sbi = ll_i2sbi(inode); struct ptlrpc_request *req = NULL; const char *pv = value; + char *fullname; __u64 valid; int rc; @@ -141,10 +141,13 @@ ll_xattr_set_common(const struct xattr_handler *handler, return -EPERM; } - sprintf(fullname, "%s%s\n", handler->prefix, name); + fullname = kasprintf(GFP_KERNEL, "%s%s\n", handler->prefix, name); + if (!fullname) + return -ENOMEM; rc = md_setxattr(sbi->ll_md_exp, ll_inode2fid(inode), valid, fullname, pv, size, 0, flags, ll_i2suppgid(inode), &req); + kfree(fullname); if (rc) { if (rc == -EOPNOTSUPP && handler->flags == XATTR_USER_T) { LCONSOLE_INFO("Disabling user_xattr feature because it is not supported on the server\n"); @@ -364,11 +367,11 @@ static int ll_xattr_get_common(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, size_t size) { - char fullname[strlen(handler->prefix) + strlen(name) + 1]; struct ll_sb_info *sbi = ll_i2sbi(inode); #ifdef CONFIG_FS_POSIX_ACL struct ll_inode_info *lli = ll_i2info(inode); #endif + char *fullname; int rc; CDEBUG(D_VFSTRACE, "VFS Op:inode=" DFID "(%p)\n", @@ -411,9 +414,13 @@ static int ll_xattr_get_common(const struct xattr_handler *handler, if (handler->flags == XATTR_ACL_DEFAULT_T && !S_ISDIR(inode->i_mode)) return -ENODATA; #endif - sprintf(fullname, "%s%s\n", handler->prefix, name); - return ll_xattr_list(inode, fullname, handler->flags, buffer, size, - OBD_MD_FLXATTR); + fullname = kasprintf(GFP_KERNEL, "%s%s\n", handler->prefix, name); + if (!fullname) + return -ENOMEM; + rc = ll_xattr_list(inode, fullname, handler->flags, buffer, size, + OBD_MD_FLXATTR); + kfree(fullname); + return rc; } static ssize_t ll_getxattr_lov(struct inode *inode, void *buf, size_t buf_size) -- 2.7.4 -- Kees Cook Pixel Security
