From: "[email protected]" <[email protected]>
[ Upstream commit 514ca14ed5444b911de59ed3381dfd195d99fe4b ]
Back during the discussion of
commit a9a3ed1eff36 ("x86: Fix early boot crash on gcc-10, third try")
we discussed the need for a function attribute to control the omission
of stack protectors on a per-function basis; at the time Clang had
support for no_stack_protector but GCC did not. This was fixed in
gcc-11. Now that the function attribute is available, let's start using
it.
Callers of boot_init_stack_canary need to use this function attribute
unless they're compiled with -fno-stack-protector, otherwise the canary
stored in the stack slot of the caller will differ upon the call to
boot_init_stack_canary. This will lead to a call to __stack_chk_fail()
then panic.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94722
Link:
https://lore.kernel.org/all/[email protected]/
Tested-by: Nathan Chancellor <[email protected]>
Acked-by: Michael Ellerman <[email protected]> (powerpc)
Acked-by: Miguel Ojeda <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Nick Desaulniers <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: [email protected] <[email protected]>
[ Backport to 6.1.y: retain this tree's start_kernel() signature, which
predates its upstream __noreturn annotation, and add
__no_stack_protector. ]
Assisted-by: LLM
Signed-off-by: Artem Dinaburg <[email protected]>
---
Hi Greg, Sasha, and kernel and powerpc maintainers,
I am continuing CVE backports still missing from 6.1.y.
This fix is inherited by v6.6 and every later mainline release, but 6.1.y
still has the affected code. The target-specific adjustment is described
in the bracketed note above.
Could you please queue it for 6.1.y?
Thanks,
Artem Dinaburg
CVE: CVE-2023-53491
Build validation: The touched powerpc allmodconfig objects built
with CONFIG_WERROR=y, and the patched functions had no stack_chk_fail
reference.
AI assistance: An LLM helped find, adapt, and validate this
backport; I reviewed the patch and test output.
arch/powerpc/kernel/smp.c | 1 +
include/linux/compiler_attributes.h | 12 ++++++++++++
init/main.c | 3 ++-
3 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 980f2bc832d98d..fa17fdcc55a3de 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1608,6 +1608,7 @@ static void add_cpu_to_masks(int cpu)
}
/* Activate a secondary processor. */
+__no_stack_protector
void start_secondary(void *unused)
{
unsigned int cpu = raw_smp_processor_id();
diff --git a/include/linux/compiler_attributes.h
b/include/linux/compiler_attributes.h
index ab1fe28162b5e8..b9778e13b0a085 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -277,6 +277,18 @@
*/
#define __noreturn __attribute__((__noreturn__))
+/*
+ * Optional: only supported since GCC >= 11.1, clang >= 7.0.
+ *
+ * gcc:
https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fstack_005fprotector-function-attribute
+ * clang:
https://clang.llvm.org/docs/AttributeReference.html#no-stack-protector-safebuffers
+ */
+#if __has_attribute(__no_stack_protector__)
+# define __no_stack_protector __attribute__((__no_stack_protector__))
+#else
+# define __no_stack_protector
+#endif
+
/*
* Optional: not supported by gcc.
* Optional: not supported by icc.
diff --git a/init/main.c b/init/main.c
index 50b84f1f9ff38a..6acfd5a78bd7a5 100644
--- a/init/main.c
+++ b/init/main.c
@@ -908,7 +908,8 @@ static void __init print_unknown_bootoptions(void)
memblock_free(unknown_options, len);
}
-asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
+asmlinkage __visible __init __no_sanitize_address __no_stack_protector
+void start_kernel(void)
{
char *command_line;
char *after_dashes;
--
2.39.5
