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check_native: Get rid of alloca

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Use malloc rather than alloca to avoid potential stack overflow.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Joe Simmons-Talbott 2023-06-13 10:05:03 -04:00 • committed by Adhemerval Zanella
parent 48170127d9
commit 9a17a193b4
1 changed files with 11 additions and 24 deletions
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35
sysdeps/unix/sysv/linux/check_native.c
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@ -48,11 +48,20 @@ __check_native (uint32_t a1_index, int *a1_native,
nladdr.nl_family = AF_NETLINK; nladdr.nl_family = AF_NETLINK;
socklen_t addr_len = sizeof (nladdr); socklen_t addr_len = sizeof (nladdr);
bool use_malloc = false;
if (fd < 0) if (fd < 0)
return; return;
/* Netlink requires that user buffer needs to be either 8kb or page size
(whichever is bigger), however this has been changed over time and now
8Kb is sufficient (check NLMSG_DEFAULT_SIZE on Linux
linux/include/linux/netlink.h). */
const size_t buf_size = 8192;
char *buf = malloc (buf_size);
if (buf == NULL)
goto out;
if (__bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) != 0 if (__bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) != 0
|| __getsockname (fd, (struct sockaddr *) &nladdr, &addr_len) != 0) || __getsockname (fd, (struct sockaddr *) &nladdr, &addr_len) != 0)
goto out; goto out;
@ -81,26 +90,6 @@ __check_native (uint32_t a1_index, int *a1_native,
memset (&nladdr, '\0', sizeof (nladdr)); memset (&nladdr, '\0', sizeof (nladdr));
nladdr.nl_family = AF_NETLINK; nladdr.nl_family = AF_NETLINK;
#ifdef PAGE_SIZE
/* Help the compiler optimize out the malloc call if PAGE_SIZE
is constant and smaller or equal to PTHREAD_STACK_MIN/4. */
const size_t buf_size = PAGE_SIZE;
#else
const size_t buf_size = __getpagesize ();
#endif
char *buf;
if (__libc_use_alloca (buf_size))
buf = alloca (buf_size);
else
{
buf = malloc (buf_size);
if (buf != NULL)
use_malloc = true;
else
goto out;
}
struct iovec iov = { buf, buf_size }; struct iovec iov = { buf, buf_size };
if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0, if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0,
@ -170,7 +159,5 @@ __check_native (uint32_t a1_index, int *a1_native,
out: out:
__close_nocancel_nostatus (fd); __close_nocancel_nostatus (fd);
free (buf);
if (use_malloc)
free (buf);
} }