Messages in this thread | | | Date | Thu, 1 Jun 2023 09:45:57 -0700 | Subject | Re: [PATCH] x86/purgatory: Do not use fortified string functions | From | Dave Hansen <> |
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On 5/30/23 17:33, Kees Cook wrote: > With the addition of -fstrict-flex-arrays=3, struct sha256_state's > trailing array is no longer ignored by CONFIG_FORTIFY_SOURCE: > > struct sha256_state { > u32 state[SHA256_DIGEST_SIZE / 4]; > u64 count; > u8 buf[SHA256_BLOCK_SIZE]; > }; > > This means that the memcpy() calls with "buf" as a destination in > sha256.c's code will attempt to perform run-time bounds checking, which > could lead to calling missing functions, specifically a potential > WARN_ONCE, which isn't callable from purgatory. > > Reported-by: Thorsten Leemhuis <linux@leemhuis.info> > Closes: https://lore.kernel.org/lkml/175578ec-9dec-7a9c-8d3a-43f24ff86b92@leemhuis.info/ > Bisected-by: "Joan Bruguera Micó" <joanbrugueram@gmail.com> > Fixes: df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com>
Hi Folks,
The -fstrict-flex-arrays=3 commit isn't upstream yet, right? That makes it a _bit_ wonky for us to carry this on the x86 side since among other things, the Fixes commit doesn't exist. I'd be fine if this goes up along with the -fstrict-flex-arrays=3 code, so:
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
We could also pick it up from the x86 side, but I think that would need a _bit_ of a different commit message to allude to it being to prepare for the _future_ setting of -fstrict-flex-arrays=3 and having no practical benefits now.
Let me know if you don't want to send this up with the -fstrict-flex-arrays=3 set.
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