| From | Ben Hutchings <> | Date | Wed, 15 Feb 2017 22:41:34 +0000 | Subject | [PATCH 3.2 038/126] fuse: listxattr: verify xattr list |
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3.2.85-rc1 review patch. If anyone has any objections, please let me know.
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From: Miklos Szeredi <mszeredi@redhat.com>
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 <mszeredi@redhat.com> [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1536,6 +1536,23 @@ static ssize_t fuse_getxattr(struct dent 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 den } 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;
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