File virtiofsd-Save-error-code-early-at-the-f.patch of Package qemu.21547
From: Vivek Goyal <vgoyal@redhat.com>
Date: Mon, 8 Feb 2021 17:40:23 -0500
Subject: virtiofsd: Save error code early at the failure callsite
Git-commit: 1e08f164e9fdc9528ad6990012301b9a04b0bc90
References: bsc#1183373, CVE-2021-20263
Change error code handling slightly in lo_setattr(). Right now we seem
to jump to out_err and assume that "errno" is valid and use that to
send reply.
But if caller has to do some other operations before jumping to out_err,
then it does the dance of first saving errno to saverr and the restore
errno before jumping to out_err. This makes it more confusing.
I am about to make more changes where caller will have to do some
work after error before jumping to out_err. I found it easier to
change the convention a bit. That is caller saves error in "saverr"
before jumping to out_err. And out_err uses "saverr" to send error
back and does not rely on "errno" having actual error.
v3: Resolved conflicts in lo_setattr() due to lo_inode_open() changes.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210208224024.43555-2-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
tools/virtiofsd/passthrough_ll.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 90f5281f10ab747098e57a3157c1..200a1d26bd11bcde5729c4f33195 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -710,6 +710,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
res = fchmodat(lo->proc_self_fd, procname, attr->st_mode, 0);
}
if (res == -1) {
+ saverr = errno;
goto out_err;
}
}
@@ -719,6 +720,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
res = fchownat(ifd, "", uid, gid, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
if (res == -1) {
+ saverr = errno;
goto out_err;
}
}
@@ -730,16 +732,15 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
} else {
truncfd = lo_inode_open(lo, inode, O_RDWR);
if (truncfd < 0) {
- errno = -truncfd;
+ saverr = -truncfd;
goto out_err;
}
}
res = ftruncate(truncfd, attr->st_size);
+ saverr = res == -1 ? errno : 0;
if (!fi) {
- saverr = errno;
close(truncfd);
- errno = saverr;
}
if (res == -1) {
goto out_err;
@@ -772,6 +773,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
res = utimensat(lo->proc_self_fd, procname, tv, 0);
}
if (res == -1) {
+ saverr = errno;
goto out_err;
}
}
@@ -780,7 +782,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
return lo_getattr(req, ino, fi);
out_err:
- saverr = errno;
lo_inode_put(lo, &inode);
fuse_reply_err(req, saverr);
}