From 269d193820342dc109f39909d78fb30f4c978f76 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 9 Feb 2023 11:52:44 -0500 Subject: fix wrong sigaction syscall ABI on mips*, or1k, microblaze, riscv64 we wrongly defined a dummy SA_RESTORER flag on these archs, despite the kernel interface not actually having such a feature. on archs which lack SA_RESTORER, the kernel sigaction structure also lacks the restorer function pointer member, which means the signal mask appears at a different offset. the kernel was thereby interpreting the bits of the code address as part of the signal set to be masked while handling the signal. this patch removes the erroneous SA_RESTORER definitions from archs which do not have it, makes access to the member conditional on whether SA_RESTORER is defined for the arch, and removes the now-unused asm for the affected archs. because there are reportedly versions of qemu-user which also use the wrong ABI here, the old ksigaction struct size is preserved with an unused member at the end. this is harmless and mitigates the risk of such a bug turning into a buffer overflow onto the sigaction function's stack. --- arch/mips/bits/signal.h | 1 - arch/mips/ksigaction.h | 5 +---- 2 files changed, 1 insertion(+), 5 deletions(-) (limited to 'arch/mips') diff --git a/arch/mips/bits/signal.h b/arch/mips/bits/signal.h index 1b69e762..a3b3857a 100644 --- a/arch/mips/bits/signal.h +++ b/arch/mips/bits/signal.h @@ -66,7 +66,6 @@ typedef struct __ucontext { #define SA_RESTART 0x10000000 #define SA_NODEFER 0x40000000 #define SA_RESETHAND 0x80000000 -#define SA_RESTORER 0x04000000 #undef SIG_BLOCK #undef SIG_UNBLOCK diff --git a/arch/mips/ksigaction.h b/arch/mips/ksigaction.h index 63fdfab0..485abf75 100644 --- a/arch/mips/ksigaction.h +++ b/arch/mips/ksigaction.h @@ -4,10 +4,7 @@ struct k_sigaction { unsigned flags; void (*handler)(int); unsigned long mask[4]; - /* The following field is past the end of the structure the - * kernel will read or write, and exists only to avoid having - * mips-specific preprocessor conditionals in sigaction.c. */ - void (*restorer)(); + void *unused; }; hidden void __restore(), __restore_rt(); -- cgit 1.4.1