There are so many places that build struct siginfo by hand that at least one of them is bound to get it wrong. A handful of cases in the kernel arguably did just that when using the errno field of siginfo to pass no errno values to userspace. The usage is limited to a single si_code so at least does not mess up anything else.
Encapsulate this questionable pattern in a helper function so that the userspace ABI is preserved. Update all of the places that use this pattern to use the new helper function. Signed-off-by: "Eric W. Biederman" <[email protected]> --- arch/arm/kernel/ptrace.c | 8 +------- arch/arm64/kernel/ptrace.c | 6 ++++-- arch/powerpc/kernel/process.c | 9 ++------- arch/xtensa/kernel/ptrace.c | 8 +------- include/linux/sched/signal.h | 2 ++ kernel/signal.c | 15 +++++++++++++++ 6 files changed, 25 insertions(+), 23 deletions(-) diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c index 58e3771e4c5b..7724b0f661b3 100644 --- a/arch/arm/kernel/ptrace.c +++ b/arch/arm/kernel/ptrace.c @@ -390,7 +390,6 @@ static void ptrace_hbptriggered(struct perf_event *bp, struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp); long num; int i; - siginfo_t info; for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i) if (current->thread.debug.hbp[i] == bp) @@ -398,12 +397,7 @@ static void ptrace_hbptriggered(struct perf_event *bp, num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i); - info.si_signo = SIGTRAP; - info.si_errno = (int)num; - info.si_code = TRAP_HWBKPT; - info.si_addr = (void __user *)(bkpt->trigger); - - force_sig_info(SIGTRAP, &info, current); + force_sig_ptrace_errno_trap((int)num, (void __user *)(bkpt->trigger)); } /* diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 95daa1478a7c..6618036ae6d4 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -190,21 +190,23 @@ static void ptrace_hbptriggered(struct perf_event *bp, #ifdef CONFIG_COMPAT if (is_compat_task()) { + int si_errno = 0; int i; for (i = 0; i < ARM_MAX_BRP; ++i) { if (current->thread.debug.hbp_break[i] == bp) { - info.si_errno = (i << 1) + 1; + si_errno = (i << 1) + 1; break; } } for (i = 0; i < ARM_MAX_WRP; ++i) { if (current->thread.debug.hbp_watch[i] == bp) { - info.si_errno = -((i << 1) + 1); + si_errno = -((i << 1) + 1); break; } } + force_sig_ptrace_errno_trap(si_errno, (void __user *)bkpt->trigger); } #endif force_sig_info(SIGTRAP, &info, current); diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index bfb48cf56bc3..4208cbe2fb7f 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -603,19 +603,14 @@ EXPORT_SYMBOL(flush_all_to_thread); void do_send_trap(struct pt_regs *regs, unsigned long address, unsigned long error_code, int breakpt) { - siginfo_t info; - current->thread.trap_nr = TRAP_HWBKPT; if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code, 11, SIGSEGV) == NOTIFY_STOP) return; /* Deliver the signal to userspace */ - info.si_signo = SIGTRAP; - info.si_errno = breakpt; /* breakpoint or watchpoint id */ - info.si_code = TRAP_HWBKPT; - info.si_addr = (void __user *)address; - force_sig_info(SIGTRAP, &info, current); + force_sig_ptrace_errno_trap(breakpt, /* breakpoint or watchpoint id */ + (void __user *)address); } #else /* !CONFIG_PPC_ADV_DEBUG_REGS */ void do_break (struct pt_regs *regs, unsigned long address, diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c index e2461968efb2..c0845cb1cbb9 100644 --- a/arch/xtensa/kernel/ptrace.c +++ b/arch/xtensa/kernel/ptrace.c @@ -278,7 +278,6 @@ static void ptrace_hbptriggered(struct perf_event *bp, struct pt_regs *regs) { int i; - siginfo_t info; struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp); if (bp->attr.bp_type & HW_BREAKPOINT_X) { @@ -293,12 +292,7 @@ static void ptrace_hbptriggered(struct perf_event *bp, i = (i << 1) | 1; } - info.si_signo = SIGTRAP; - info.si_errno = i; - info.si_code = TRAP_HWBKPT; - info.si_addr = (void __user *)bkpt->address; - - force_sig_info(SIGTRAP, &info, current); + force_sig_ptrace_errno_trap(i, (void __user *)bkpt->address); } static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 944fe6356f4a..23b4f9cb82db 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -311,6 +311,8 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *); int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper); int force_sig_pkuerr(void __user *addr, u32 pkey); +int force_sig_ptrace_errno_trap(int errno, void __user *addr); + extern int send_sig_info(int, struct siginfo *, struct task_struct *); extern int force_sigsegv(int, struct task_struct *); extern int force_sig_info(int, struct siginfo *, struct task_struct *); diff --git a/kernel/signal.c b/kernel/signal.c index 4f6300ef8062..e549174c0831 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1599,6 +1599,21 @@ int force_sig_pkuerr(void __user *addr, u32 pkey) } #endif +/* For the crazy architectures that include trap information in + * the errno field, instead of an actual errno value. + */ +int force_sig_ptrace_errno_trap(int errno, void __user *addr) +{ + struct siginfo info; + + clear_siginfo(&info); + info.si_signo = SIGTRAP; + info.si_errno = errno; + info.si_code = TRAP_HWBKPT; + info.si_addr = addr; + return force_sig_info(info.si_signo, &info, current); +} + int kill_pgrp(struct pid *pid, int sig, int priv) { int ret; -- 2.14.1
