* Vivek Goyal (vgo...@redhat.com) wrote:
> getxattr/setxattr/removexattr/listxattr operations handle regualar
> and non-regular files differently. For the case of non-regular files
> we do fchdir(/proc/self/fd) and the xattr operation and then revert
> back to original working directory. After this we are saving errno
> and that's buggy because fchdir() will overwrite the errno.
>
> FCHDIR_NOFAIL(lo->proc_self_fd);
> ret = getxattr(procname, name, value, size);
> FCHDIR_NOFAIL(lo->root.fd);
>
> if (ret == -1)
> saverr = errno
>
> In above example, if getxattr() failed, we will still return 0 to caller
> as errno must have been written by FCHDIR_NOFAIL(lo->root.fd) call.
> Fix all such instances and capture "errno" early and save in "saverr"
> variable.
>
> Signed-off-by: Vivek Goyal <vgo...@redhat.com>
I think the existing code is actually safe; I don't think fchdir
will/should set errno unless there's an error, and we're explictly
asserting there isn't one.
However, I do prefer doing this save since we already have the save
variables and it makes the chance of screwing it up from any other
forgotten syscall less likely, so
Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> ---
> tools/virtiofsd/passthrough_ll.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/tools/virtiofsd/passthrough_ll.c
> b/tools/virtiofsd/passthrough_ll.c
> index 49c21fd855..ec91b3c133 100644
> --- a/tools/virtiofsd/passthrough_ll.c
> +++ b/tools/virtiofsd/passthrough_ll.c
> @@ -2791,15 +2791,17 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t
> ino, const char *in_name,
> goto out_err;
> }
> ret = fgetxattr(fd, name, value, size);
> + saverr = ret == -1 ? errno : 0;
> } else {
> /* fchdir should not fail here */
> FCHDIR_NOFAIL(lo->proc_self_fd);
> ret = getxattr(procname, name, value, size);
> + saverr = ret == -1 ? errno : 0;
> FCHDIR_NOFAIL(lo->root.fd);
> }
>
> if (ret == -1) {
> - goto out_err;
> + goto out;
> }
> if (size) {
> saverr = 0;
> @@ -2864,15 +2866,17 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t
> ino, size_t size)
> goto out_err;
> }
> ret = flistxattr(fd, value, size);
> + saverr = ret == -1 ? errno : 0;
> } else {
> /* fchdir should not fail here */
> FCHDIR_NOFAIL(lo->proc_self_fd);
> ret = listxattr(procname, value, size);
> + saverr = ret == -1 ? errno : 0;
> FCHDIR_NOFAIL(lo->root.fd);
> }
>
> if (ret == -1) {
> - goto out_err;
> + goto out;
> }
> if (size) {
> saverr = 0;
> @@ -2998,15 +3002,15 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t
> ino, const char *in_name,
> goto out;
> }
> ret = fsetxattr(fd, name, value, size, flags);
> + saverr = ret == -1 ? errno : 0;
> } else {
> /* fchdir should not fail here */
> FCHDIR_NOFAIL(lo->proc_self_fd);
> ret = setxattr(procname, name, value, size, flags);
> + saverr = ret == -1 ? errno : 0;
> FCHDIR_NOFAIL(lo->root.fd);
> }
>
> - saverr = ret == -1 ? errno : 0;
> -
> out:
> if (fd >= 0) {
> close(fd);
> @@ -3064,15 +3068,15 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t
> ino, const char *in_name)
> goto out;
> }
> ret = fremovexattr(fd, name);
> + saverr = ret == -1 ? errno : 0;
> } else {
> /* fchdir should not fail here */
> FCHDIR_NOFAIL(lo->proc_self_fd);
> ret = removexattr(procname, name);
> + saverr = ret == -1 ? errno : 0;
> FCHDIR_NOFAIL(lo->root.fd);
> }
>
> - saverr = ret == -1 ? errno : 0;
> -
> out:
> if (fd >= 0) {
> close(fd);
> --
> 2.25.4
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
