Re: [PATCH v7 5/6] x86/signal: Detect and prevent an alternate signal stack overflow
flat view
From: Borislav Petkov <hidden>
Date: 2021-03-16 11:53:39
Also in:
linux-arch, lkml
On Mon, Mar 15, 2021 at 11:52:14PM -0700, Chang S. Bae wrote:
quoted hunk ↗ jump to hunk
@@ -272,7 +275,8 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, * If we are on the alternate signal stack and would overflow it, don't. * Return an always-bogus address instead so we will die with SIGSEGV. */ - if (onsigstack && !likely(on_sig_stack(sp))) + if (onsigstack && unlikely(sp <= current->sas_ss_sp || + sp - current->sas_ss_sp > current->sas_ss_size)) return (void __user *)-1L;
So clearly I'm missing something because trying to trigger the test case in the bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=153531 on current tip/master doesn't work. Runs with MY_MINSIGSTKSZ under 2048 fail with: tst-minsigstksz-2: sigaltstack: Cannot allocate memory and above 2048 don't overwrite bytes below the stack. So something else is missing. How did you test this patch? Thx. -- Regards/Gruss, Boris. SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg