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authorDJ Delorie <dj@delorie.com>2017-07-14 21:46:42 -0400
committerDJ Delorie <dj@delorie.com>2017-07-14 21:46:42 -0400
commit4fa8ae49aa169fb8d97882938e8bee3ed9ce5410 (patch)
tree61b1f4b60f4c03f089c210a33714138516ddb57b
parentde895ddcd7fc45caeeeb0ae312311b8bd31d82c5 (diff)
downloadglibc-4fa8ae49aa169fb8d97882938e8bee3ed9ce5410.tar.gz
Fix BZ #21654 - grp-merge.c alignment
* grp/grp_merge.c (__copy_grp): Align char** to minimum pointer alignment not char alignment. (__merge_grp): Likewise.
-rw-r--r--ChangeLog7
-rw-r--r--grp/grp-merge.c16
2 files changed, 23 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index 96c76f72ec..a9044a588c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+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.
+
2017-07-14 Szabolcs Nagy <szabolcs.nagy@arm.com>
Florian Weimer <fweimer@redhat.com>
diff --git a/grp/grp-merge.c b/grp/grp-merge.c
index 77c494d159..6590e5d823 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];