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virtiofsd: Fix xattr operations overwriting errno 

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 <vgoyal@redhat.com>
Message-Id: <20210622150852.1507204-3-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Vivek Goyal 2021-06-22 11:08:47 -04:00 committed by Dr. David Alan Gilbert
parent 061624455f
commit 5290fb625d
1 changed files with 10 additions and 6 deletions
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16
tools/virtiofsd/passthrough_ll.c
View File

@ -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);