[2.24 COMMITTED] Fix BZ #21654 - grp-merge.c alignment
Florian Weimer
fweimer@redhat.com
Sun Jan 1 00:00:00 GMT 2017
From: DJ Delorie <dj@delorie.com>
* grp/grp_merge.c (__copy_grp): Align char** to minimum pointer
alignment not char alignment.
(__merge_grp): Likewise.
(cherry picked from commit 4fa8ae49aa169fb8d97882938e8bee3ed9ce5410)
2017-07-14 DJ Delorie <dj@redhat.com>
[BZ #21654]
* grp/grp_merge.c (__copy_grp): Align char** to minimum pointer
alignment not char alignment.
(__merge_grp): Likewise.
diff --git a/grp/grp-merge.c b/grp/grp-merge.c
index 0a1eb38d2c..50573b8986 100644
--- a/grp/grp-merge.c
+++ b/grp/grp-merge.c
@@ -85,6 +85,14 @@ __copy_grp (const struct group srcgrp, const size_t buflen,
}
members[i] = NULL;
+ /* Align for pointers. We can't simply align C because we need to
+ align destbuf[c]. */
+ if ((((uintptr_t)destbuf + c) & (__alignof__(char **) - 1)) != 0)
+ {
+ uintptr_t mis_align = ((uintptr_t)destbuf + c) & (__alignof__(char **) - 1);
+ c += __alignof__(char **) - mis_align;
+ }
+
/* Copy the pointers from the members array into the buffer and assign them
to the gr_mem member of destgrp. */
destgrp->gr_mem = (char **) &destbuf[c];
@@ -168,6 +176,14 @@ __merge_grp (struct group *savedgrp, char *savedbuf, char *savedend,
/* Add the NULL-terminator. */
members[savedmemcount + memcount] = NULL;
+ /* Align for pointers. We can't simply align C because we need to
+ align savedbuf[c]. */
+ if ((((uintptr_t)savedbuf + c) & (__alignof__(char **) - 1)) != 0)
+ {
+ uintptr_t mis_align = ((uintptr_t)savedbuf + c) & (__alignof__(char **) - 1);
+ c += __alignof__(char **) - mis_align;
+ }
+
/* Copy the member array back into the buffer after the member list and free
the member array. */
savedgrp->gr_mem = (char **) &savedbuf[c];
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