From cb1bf2f321b45a06447133b3db00621b7300c456 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Mon, 2 Nov 2015 12:39:28 -0500 Subject: [PATCH] properly access mcontext_t program counter in cancellation handler using the actual mcontext_t definition rather than an overlaid pointer array both improves correctness/readability and eliminates some ugly hacks for archs with 64-bit registers bit 32-bit program counter. also fix UB due to comparison of pointers not in a common array object. --- arch/aarch64/pthread_arch.h | 2 +- arch/arm/pthread_arch.h | 2 +- arch/i386/pthread_arch.h | 2 +- arch/microblaze/pthread_arch.h | 2 +- arch/mips/pthread_arch.h | 2 +- arch/or1k/pthread_arch.h | 3 +-- arch/powerpc/pthread_arch.h | 3 +-- arch/sh/pthread_arch.h | 2 +- arch/x32/pthread_arch.h | 2 +- arch/x86_64/pthread_arch.h | 2 +- src/thread/pthread_cancel.c | 7 ++++--- 11 files changed, 14 insertions(+), 15 deletions(-) diff --git a/arch/aarch64/pthread_arch.h b/arch/aarch64/pthread_arch.h index 74276f4..b2e2d8f 100644 --- a/arch/aarch64/pthread_arch.h +++ b/arch/aarch64/pthread_arch.h @@ -8,4 +8,4 @@ static inline struct pthread *__pthread_self() #define TLS_ABOVE_TP #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) - 16) -#define CANCEL_REG_IP 33 +#define MC_PC pc diff --git a/arch/arm/pthread_arch.h b/arch/arm/pthread_arch.h index 4a4dd09..8b8a7fb 100644 --- a/arch/arm/pthread_arch.h +++ b/arch/arm/pthread_arch.h @@ -27,4 +27,4 @@ static inline pthread_t __pthread_self() #define TLS_ABOVE_TP #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) - 8) -#define CANCEL_REG_IP 18 +#define MC_PC arm_pc diff --git a/arch/i386/pthread_arch.h b/arch/i386/pthread_arch.h index 1c06c76..7f38a56 100644 --- a/arch/i386/pthread_arch.h +++ b/arch/i386/pthread_arch.h @@ -7,4 +7,4 @@ static inline struct pthread *__pthread_self() #define TP_ADJ(p) (p) -#define CANCEL_REG_IP 14 +#define MC_PC gregs[REG_EIP] diff --git a/arch/microblaze/pthread_arch.h b/arch/microblaze/pthread_arch.h index 259d3d6..08d1ba7 100644 --- a/arch/microblaze/pthread_arch.h +++ b/arch/microblaze/pthread_arch.h @@ -7,4 +7,4 @@ static inline struct pthread *__pthread_self() #define TP_ADJ(p) (p) -#define CANCEL_REG_IP 32 +#define MC_PC regs.pc diff --git a/arch/mips/pthread_arch.h b/arch/mips/pthread_arch.h index 93edbd4..8a49965 100644 --- a/arch/mips/pthread_arch.h +++ b/arch/mips/pthread_arch.h @@ -16,4 +16,4 @@ static inline struct pthread *__pthread_self() #define DTP_OFFSET 0x8000 -#define CANCEL_REG_IP (3-(union {int __i; char __b;}){1}.__b) +#define MC_PC pc diff --git a/arch/or1k/pthread_arch.h b/arch/or1k/pthread_arch.h index ad63169..7decd76 100644 --- a/arch/or1k/pthread_arch.h +++ b/arch/or1k/pthread_arch.h @@ -14,5 +14,4 @@ static inline struct pthread *__pthread_self() #define TLS_ABOVE_TP #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread)) -/* word-offset to 'pc' in mcontext_t */ -#define CANCEL_REG_IP 32 +#define MC_PC regs.pc diff --git a/arch/powerpc/pthread_arch.h b/arch/powerpc/pthread_arch.h index bb7405d..7c5c4fa 100644 --- a/arch/powerpc/pthread_arch.h +++ b/arch/powerpc/pthread_arch.h @@ -15,9 +15,8 @@ static inline struct pthread *__pthread_self() #define DTP_OFFSET 0x8000 -// offset of the PC register in mcontext_t, divided by the system wordsize // the kernel calls the ip "nip", it's the first saved value after the 32 // GPRs. -#define CANCEL_REG_IP 32 +#define MC_PC gregs[32] #define CANARY canary_at_end diff --git a/arch/sh/pthread_arch.h b/arch/sh/pthread_arch.h index 65c389f..2756e7e 100644 --- a/arch/sh/pthread_arch.h +++ b/arch/sh/pthread_arch.h @@ -8,4 +8,4 @@ static inline struct pthread *__pthread_self() #define TLS_ABOVE_TP #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) - 8) -#define CANCEL_REG_IP 17 +#define MC_PC sc_pc diff --git a/arch/x32/pthread_arch.h b/arch/x32/pthread_arch.h index 033bfd6..ecb0bbf 100644 --- a/arch/x32/pthread_arch.h +++ b/arch/x32/pthread_arch.h @@ -7,6 +7,6 @@ static inline struct pthread *__pthread_self() #define TP_ADJ(p) (p) -#define CANCEL_REG_IP 32 +#define MC_PC gregs[REG_RIP] #define CANARY canary2 diff --git a/arch/x86_64/pthread_arch.h b/arch/x86_64/pthread_arch.h index 29e4590..c61509c 100644 --- a/arch/x86_64/pthread_arch.h +++ b/arch/x86_64/pthread_arch.h @@ -7,4 +7,4 @@ static inline struct pthread *__pthread_self() #define TP_ADJ(p) (p) -#define CANCEL_REG_IP 16 +#define MC_PC gregs[REG_RIP] diff --git a/src/thread/pthread_cancel.c b/src/thread/pthread_cancel.c index 0151a1a..6eaf72c 100644 --- a/src/thread/pthread_cancel.c +++ b/src/thread/pthread_cancel.c @@ -1,3 +1,4 @@ +#define _GNU_SOURCE #include #include "pthread_impl.h" #include "syscall.h" @@ -61,15 +62,15 @@ static void cancel_handler(int sig, siginfo_t *si, void *ctx) { pthread_t self = __pthread_self(); ucontext_t *uc = ctx; - const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP]; + uintptr_t pc = uc->uc_mcontext.MC_PC; a_barrier(); if (!self->cancel || self->canceldisable == PTHREAD_CANCEL_DISABLE) return; _sigaddset(&uc->uc_sigmask, SIGCANCEL); - if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) { - ((char **)&uc->uc_mcontext)[CANCEL_REG_IP] = (char *)__cp_cancel; + if (self->cancelasync || pc >= (uintptr_t)__cp_begin && pc < (uintptr_t)__cp_end) { + uc->uc_mcontext.MC_PC = (uintptr_t)__cp_cancel; return; } -- 2.7.0