URL: https://github.com/SSSD/sssd/pull/743
Author: alexey-tikhonov
Title: #743: lib/cifs_idmap_sss: fixed unaligned mem access
Action: opened
PR body:
"""
Fixed following warning:
```
lib/cifs_idmap_sss/cifs_idmap_sss.c: In function ‘sss_sid_to_id’:
lib/cifs_idmap_sss/cifs_idmap_sss.c:221:47: warning: taking address
of packed member of ‘struct cifs_uxid’ may result in an unaligned
pointer value [-Waddress-of-packed-member]
err = sss_nss_getidbysid(sid, (uint32_t *)&cuxid->id.uid, &id_type);
```
Actually there are two issues:
1) Packed `cifs_uxid::id.uid` may be unaligned thus generating run time
error on some architectures (as compiler complains);
2) In theory size of `uid_t` may be different than size of `uint32_t`
thus resulting in corruption of `cifs_uxid` content.
Proposed patch is not ideal due to `(uid_t)uid` cast but solves most
of issues with minimal effor. Proper solution would require patching of
`sss_nss_getidbysid()` and all underlying functions for no good reason.
"""
To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/743/head:pr743
git checkout pr743
From 0fe0948725341c3474ad64656df365e113acf67f Mon Sep 17 00:00:00 2001
From: Alexey Tikhonov <atikh...@redhat.com>
Date: Tue, 5 Feb 2019 16:34:31 +0100
Subject: [PATCH] lib/cifs_idmap_sss: fixed unaligned mem access
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Fixed following warning:
```
lib/cifs_idmap_sss/cifs_idmap_sss.c: In function ‘sss_sid_to_id’:
lib/cifs_idmap_sss/cifs_idmap_sss.c:221:47: warning: taking address
of packed member of ‘struct cifs_uxid’ may result in an unaligned
pointer value [-Waddress-of-packed-member]
err = sss_nss_getidbysid(sid, (uint32_t *)&cuxid->id.uid, &id_type);
```
Actually there are two issues:
1) Packed `cifs_uxid::id.uid` may be unaligned thus generating run time
error on some architectures (as compiler complains);
2) In theory size of `uid_t` may be different than size of `uint32_t`
thus resulting in corruption of `cifs_uxid` content.
Proposed patch is not ideal due to `(uid_t)uid` cast but solves most
of issues with minimal effor. Proper solution would require patching of
`sss_nss_getidbysid()` and all underlying functions for no good reason.
---
src/lib/cifs_idmap_sss/cifs_idmap_sss.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/lib/cifs_idmap_sss/cifs_idmap_sss.c b/src/lib/cifs_idmap_sss/cifs_idmap_sss.c
index e7a0b83709..6434f4b677 100644
--- a/src/lib/cifs_idmap_sss/cifs_idmap_sss.c
+++ b/src/lib/cifs_idmap_sss/cifs_idmap_sss.c
@@ -217,12 +217,14 @@ static int sss_sid_to_id(struct sssd_ctx *ctx, const char *sid,
{
int err;
enum sss_id_type id_type;
+ uint32_t uid;
- err = sss_nss_getidbysid(sid, (uint32_t *)&cuxid->id.uid, &id_type);
+ err = sss_nss_getidbysid(sid, &uid, &id_type);
if (err != 0) {
ctx_set_error(ctx, strerror(err));
return -1;
}
+ cuxid->id.uid = (uid_t)uid;
switch (id_type) {
case SSS_ID_TYPE_UID:
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