Re: [Buildroot] [PATCH] package/uclibc: Fix SSP support for RISCV32

Romain Naour via buildroot <[email protected]>
Newsgroups net.busybox.buildroot
Message-ID <[email protected]> 
Hello Waldemar, All,

Le 15/08/2026 à 21:17, Waldemar Brodkorb a écrit :
> Add patch pending upstream to fix SSP for RISCV32.
> 
> Fixes:
>   https://autobuild.buildroot.org/results/1b6/1b6f2161b11390b6545bddbc39b444401c718ebb/
> 

I tested the qemu_riscv32_virt_defconfig with uclibc-ng selected and SSP support
enabled.

Tested-by: Romain Naour <[email protected]>

Best regards,
Romain

> Signed-off-by: Waldemar Brodkorb <[email protected]>
> ---
>  .../0001-Fix-SSP-support-for-riscv32.patch    | 174 ++++++++++++++++++
>  1 file changed, 174 insertions(+)
>  create mode 100644 package/uclibc/0001-Fix-SSP-support-for-riscv32.patch
> 
> diff --git a/package/uclibc/0001-Fix-SSP-support-for-riscv32.patch b/package/uclibc/0001-Fix-SSP-support-for-riscv32.patch
> new file mode 100644
> index 0000000000..b2e38726f5
> --- /dev/null
> +++ b/package/uclibc/0001-Fix-SSP-support-for-riscv32.patch
> @@ -0,0 +1,174 @@
> +From c6efc293a52fdde7d4876243faaaa768fe052719 Mon Sep 17 00:00:00 2001
> +From: Waldemar Brodkorb <[email protected]>
> +Date: Sat, 15 Aug 2026 18:20:33 +0200
> +Subject: [PATCH] Fix SSP support for riscv32
> +
> +On modern 32-bit architectures like RISC-V (riscv32), legacy 32-bit
> +time syscalls like __NR_gettimeofday are intentionally omitted because
> +RV32 implements a strict time64-only ABI to avoid the Year 2038 bug.
> +
> +Therefore, use AT_RANDOM from the auxiliary vector first, as glibc does,
> +to obtain random data for the stack canary. If AT_RANDOM is unavailable,
> +fall back to reading random data from /dev/urandom.
> +
> +Tested with aarch64, riscv32 and riscv32 noMMU targets.
> +
> +Upstream: https://mailman.openadk.org/mailman3/hyperkitty/list/[email protected]/thread/WIKMWPXJYAPTVVZ2MMZINUJNPIJXBMOE/
> +Signed-off-by: Waldemar Brodkorb <[email protected]>
> +---
> + extra/Configs/Config.in               | 10 -------
> + ldso/include/dl-syscall.h             | 12 --------
> + ldso/ldso/ldso.c                      |  4 ++-
> + libc/misc/internals/__uClibc_main.c   |  4 ++-
> + libc/sysdeps/linux/common/dl-osinfo.h | 40 +++++++++++++++++----------
> + 5 files changed, 32 insertions(+), 38 deletions(-)
> +
> +diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in
> +index c3aabf1b4..15a072593 100644
> +--- a/extra/Configs/Config.in
> ++++ b/extra/Configs/Config.in
> +@@ -2211,16 +2211,6 @@ config UCLIBC_HAS_SSP
> + 
> + 	  Most people will answer N.
> + 
> +-config SSP_QUICK_CANARY
> +-	bool "Use simple guard values without accessing /dev/urandom"
> +-	depends on UCLIBC_HAS_SSP
> +-	help
> +-	  Use gettimeofday(2) to define the __guard without accessing
> +-	  /dev/urandom.
> +-	  WARNING: This makes smashing stack protector vulnerable to timing
> +-	  	attacks.
> +-	  Most people will answer N.
> +-
> + choice
> + 	prompt "Propolice protection blocking signal"
> + 	depends on UCLIBC_HAS_SSP
> +diff --git a/ldso/include/dl-syscall.h b/ldso/include/dl-syscall.h
> +index c143b8d45..e08b2cd41 100644
> +--- a/ldso/include/dl-syscall.h
> ++++ b/ldso/include/dl-syscall.h
> +@@ -260,18 +260,6 @@ _dl_pread(int fd, void *buf, size_t count, off_t offset)
> + }
> + #endif
> + 
> +-#ifdef __UCLIBC_HAS_SSP__
> +-# include <sys/time.h>
> +-# define __NR__dl_gettimeofday __NR_gettimeofday
> +-static __always_inline _syscall2(int, _dl_gettimeofday, struct timeval *, tv,
> +-# ifdef __USE_BSD
> +-                        struct timezone *
> +-# else
> +-                        void *
> +-# endif
> +-						, tz)
> +-#endif
> +-
> + /* Some architectures always use 12 as page shift for mmap2() eventhough the
> +  * real PAGE_SHIFT != 12.  Other architectures use the same value as
> +  * PAGE_SHIFT...
> +diff --git a/ldso/ldso/ldso.c b/ldso/ldso/ldso.c
> +index 55f7d7e45..96ee3d496 100755
> +--- a/ldso/ldso/ldso.c
> ++++ b/ldso/ldso/ldso.c
> +@@ -1225,7 +1225,9 @@ of this helper program; chances are you did not intend to run this program.\n\
> + #ifdef __UCLIBC_HAS_SSP__
> + 	_dl_debug_early("Setting up SSP guards\n");
> + 	/* Set up the stack checker's canary.  */
> +-	stack_chk_guard = _dl_setup_stack_chk_guard ();
> ++	stack_chk_guard = _dl_setup_stack_chk_guard (
> ++		_dl_auxvt[AT_RANDOM].a_type == AT_RANDOM ?
> ++		(void *)_dl_auxvt[AT_RANDOM].a_un.a_val : NULL);
> + # ifdef THREAD_SET_STACK_GUARD
> + 	THREAD_SET_STACK_GUARD (stack_chk_guard);
> + # else
> +diff --git a/libc/misc/internals/__uClibc_main.c b/libc/misc/internals/__uClibc_main.c
> +index 549606505..bbf471b17 100644
> +--- a/libc/misc/internals/__uClibc_main.c
> ++++ b/libc/misc/internals/__uClibc_main.c
> +@@ -296,7 +296,9 @@ void __uClibc_init(void)
> + #ifndef SHARED
> + # ifdef __UCLIBC_HAS_SSP__
> +     /* Set up the stack checker's canary.  */
> +-    stack_chk_guard = _dl_setup_stack_chk_guard();
> ++    stack_chk_guard = _dl_setup_stack_chk_guard(
> ++    _dl_auxvt[AT_RANDOM].a_type == AT_RANDOM ?
> ++        (void *)_dl_auxvt[AT_RANDOM].a_un.a_val : NULL);
> + #  ifdef THREAD_SET_STACK_GUARD
> +     THREAD_SET_STACK_GUARD (stack_chk_guard);
> + #  else
> +diff --git a/libc/sysdeps/linux/common/dl-osinfo.h b/libc/sysdeps/linux/common/dl-osinfo.h
> +index 3110cb05d..0a42ea094 100644
> +--- a/libc/sysdeps/linux/common/dl-osinfo.h
> ++++ b/libc/sysdeps/linux/common/dl-osinfo.h
> +@@ -21,22 +21,42 @@
> + #  ifdef IS_IN_libc
> + #   include <fcntl.h>
> + #   include <unistd.h>
> +-#   include <sys/time.h>
> ++#   include <string.h>
> + #   define OPEN open
> + #   define READ read
> + #   define CLOSE close
> +-#   define GETTIMEOFDAY gettimeofday
> ++#   define MEMCPY memcpy
> + #  else
> ++#   include <dl-string.h>
> + #   define OPEN _dl_open
> + #   define READ _dl_read
> + #   define CLOSE _dl_close
> +-#   define GETTIMEOFDAY _dl_gettimeofday
> ++#   define MEMCPY _dl_memcpy
> + #  endif
> + 
> +-static __always_inline uintptr_t _dl_setup_stack_chk_guard(void)
> ++static __always_inline uintptr_t
> ++_dl_setup_stack_chk_guard(void *dl_random)
> + {
> + 	uintptr_t ret;
> +-#  ifndef __SSP_QUICK_CANARY__
> ++
> ++	/*
> ++	 * Linux supplies random data through AT_RANDOM.
> ++	 * Use it directly when available.
> ++	 */
> ++	if (dl_random != NULL) {
> ++		MEMCPY(&ret, dl_random, sizeof(ret));
> ++
> ++#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> ++		ret &= ~(uintptr_t)0xff;
> ++#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> ++		ret &= ~((uintptr_t)0xff << (8 * (sizeof(ret) - 1)));
> ++#else
> ++# error "Unknown byte order"
> ++#endif
> ++
> ++		return ret;
> ++	}
> ++
> + 	{
> + 		int fd = OPEN("/dev/urandom", O_RDONLY, 0);
> + 		if (fd >= 0) {
> +@@ -46,18 +66,10 @@ static __always_inline uintptr_t _dl_setup_stack_chk_guard(void)
> + 				return ret;
> + 		}
> + 	}
> +-#  endif /* !__SSP_QUICK_CANARY__ */
> + 
> +-	/* Start with the "terminator canary". */
> ++	/* Fallback just the "terminator canary". */
> + 	ret = 0xFF0A0D00UL;
> + 
> +-	/* Everything failed? Or we are using a weakened model of the
> +-	 * terminator canary */
> +-	{
> +-		struct timeval tv;
> +-		if (GETTIMEOFDAY(&tv, NULL) != (-1))
> +-			ret ^= tv.tv_usec ^ tv.tv_sec;
> +-	}
> + 	return ret;
> + }
> + # endif /* libc || rtld */
> +-- 
> +2.47.3
> +

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