From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: Yu Chien Peter Lin <peterlin@andestech.com>, libc-alpha@sourceware.org
Cc: fw@deneb.enyo.de, ycliang@andestech.com, dylan@andestech.com,
alankao@andestech.com
Subject: Re: [PATCH v2] malloc: Fix clobbered errno when getrandom failed [BZ #29624]
Date: Thu, 29 Sep 2022 08:39:25 -0300 [thread overview]
Message-ID: <e01b6056-d10a-a183-330c-9e8cd906921e@linaro.org> (raw)
In-Reply-To: <20220929111323.12670-1-peterlin@andestech.com>
On 29/09/22 08:13, Yu Chien Peter Lin wrote:
> Save and restore errno when getrandom failed. On failure it will result
> in errno clobbered at statically linked program startup. This scenario
> is possible if getrandom is called by tcache_key_initialize when crng is
> not ready thus EAGAIN is returned.
>
> Fixes bug 29624.
>
> Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
> ---
> malloc/malloc.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/malloc/malloc.c b/malloc/malloc.c
> index 953183e956..823d454c99 100644
> --- a/malloc/malloc.c
> +++ b/malloc/malloc.c
> @@ -3133,9 +3133,11 @@ static uintptr_t tcache_key;
> static void
> tcache_key_initialize (void)
> {
> + int saved_errno = errno;
> if (__getrandom_nocancel (&tcache_key, sizeof(tcache_key), GRND_NONBLOCK)
> != sizeof (tcache_key))
> {
> + __set_errno(saved_errno);
> tcache_key = random_bits ();
> #if __WORDSIZE == 64
> tcache_key = (tcache_key << 32) | random_bits ();
I think it would be better to just use INTERNAL_SYSCALL now that we have all
architecture to return a negative value in case of error:
diff --git a/stdlib/arc4random.c b/stdlib/arc4random.c
index e417ef624d..20886e0445 100644
--- a/stdlib/arc4random.c
+++ b/stdlib/arc4random.c
@@ -34,7 +34,7 @@ void
__arc4random_buf (void *p, size_t n)
{
static int seen_initialized;
- size_t l;
+ int l;
int fd;
if (n == 0)
@@ -51,7 +51,7 @@ __arc4random_buf (void *p, size_t n)
n -= l;
continue; /* Interrupted by a signal; keep going. */
}
- else if (l < 0 && errno == ENOSYS)
+ else if (l < 0 && l == -ENOSYS)
break; /* No syscall, so fallback to /dev/urandom. */
arc4random_getrandom_failure ();
}
diff --git a/sysdeps/unix/sysv/linux/not-cancel.h b/sysdeps/unix/sysv/linux/not-cancel.h
index a263d294b1..00ab75a405 100644
--- a/sysdeps/unix/sysv/linux/not-cancel.h
+++ b/sysdeps/unix/sysv/linux/not-cancel.h
@@ -71,7 +71,7 @@ __writev_nocancel_nostatus (int fd, const struct iovec *iov, int iovcnt)
static inline int
__getrandom_nocancel (void *buf, size_t buflen, unsigned int flags)
{
- return INLINE_SYSCALL_CALL (getrandom, buf, buflen, flags);
+ return INTERNAL_SYSCALL_CALL (getrandom, buf, buflen, flags);
}
static inline int
next prev parent reply other threads:[~2022-09-29 11:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-29 11:13 Yu Chien Peter Lin
2022-09-29 11:39 ` Adhemerval Zanella Netto [this message]
2022-09-29 13:31 ` Florian Weimer
2022-09-29 13:51 ` Adhemerval Zanella Netto
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