* [PATCH v3] grantpt: Get rid of alloca
@ 2023-06-08 14:32 Joe Simmons-Talbott
0 siblings, 0 replies; only message in thread
From: Joe Simmons-Talbott @ 2023-06-08 14:32 UTC (permalink / raw)
To: Samuel Thibault, Sergey Bugaev, libc-alpha; +Cc: Joe Simmons-Talbott
Replace alloca with a scratch_buffer to avoid potential stack overflows.
---
Changes to v2:
* Don't set retval in scratch_buffer resize failure case since it's
already set from initialization.
sysdeps/unix/grantpt.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/sysdeps/unix/grantpt.c b/sysdeps/unix/grantpt.c
index 38fce52576..6818ee6369 100644
--- a/sysdeps/unix/grantpt.c
+++ b/sysdeps/unix/grantpt.c
@@ -20,6 +20,7 @@
#include <fcntl.h>
#include <grp.h>
#include <limits.h>
+#include <scratch_buffer.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
@@ -147,10 +148,16 @@ grantpt (int fd)
/* `sysconf' does not support _SC_GETGR_R_SIZE_MAX.
Try a moderate value. */
grbuflen = 1024;
- grtmpbuf = (char *) __alloca (grbuflen);
+ struct scratch_buffer sbuf;
+ scratch_buffer_init (&sbuf);
+ if (!scratch_buffer_set_array_size (&sbuf, 1, grbuflen))
+ goto cleanup;
+ grtmpbuf = sbuf.data;
__getgrnam_r (TTY_GROUP, &grbuf, grtmpbuf, grbuflen, &p);
if (p != NULL)
tty_gid = p->gr_gid;
+
+ scratch_buffer_free(&sbuf);
}
gid_t gid = tty_gid == -1 ? __getgid () : tty_gid;
--
2.39.2
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