From b60c85b47c061f6423cab77faf87402be5f6465a Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Sat, 1 Oct 2016 07:32:32 +0200 Subject: [PATCH] fuse: listxattr: verify xattr list commit cb3ae6d25a5471be62bfe6ac1fccc0e91edeaba0 upstream. Make sure userspace filesystem is returning a well formed list of xattr names (zero or more nonzero length, null terminated strings). [Michael Theall: only verify in the nonzero size case] Signed-off-by: Miklos Szeredi [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings --- fs/fuse/dir.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 499217e8bbe3..4041f76dd6c4 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1536,6 +1536,23 @@ static ssize_t fuse_getxattr(struct dentry *entry, const char *name, return ret; } +static int fuse_verify_xattr_list(char *list, size_t size) +{ + size_t origsize = size; + + while (size) { + size_t thislen = strnlen(list, size); + + if (!thislen || thislen == size) + return -EIO; + + size -= thislen + 1; + list += thislen + 1; + } + + return origsize; +} + static ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size) { struct inode *inode = entry->d_inode; @@ -1574,9 +1591,11 @@ static ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size) } fuse_request_send(fc, req); ret = req->out.h.error; - if (!ret) + if (!ret) { ret = size ? req->out.args[0].size : outarg.size; - else { + if (ret > 0 && size) + ret = fuse_verify_xattr_list(list, ret); + } else { if (ret == -ENOSYS) { fc->no_listxattr = 1; ret = -EOPNOTSUPP; -- 2.39.2