From 3eb0f5193b497083391aa05d35210d5645211eef Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 17 Apr 2018 15:26:37 -0500 Subject: signal: Ensure every siginfo we send has all bits initialized Call clear_siginfo to ensure every stack allocated siginfo is properly initialized before being passed to the signal sending functions. Note: It is not safe to depend on C initializers to initialize struct siginfo on the stack because C is allowed to skip holes when initializing a structure. The initialization of struct siginfo in tracehook_report_syscall_exit was moved from the helper user_single_step_siginfo into tracehook_report_syscall_exit itself, to make it clear that the local variable siginfo gets fully initialized. In a few cases the scope of struct siginfo has been reduced to make it clear that siginfo siginfo is not used on other paths in the function in which it is declared. Instances of using memset to initialize siginfo have been replaced with calls clear_siginfo for clarity. Signed-off-by: "Eric W. Biederman" --- include/linux/ptrace.h | 1 - include/linux/tracehook.h | 1 + 2 files changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 919b2a0b0307..037bf0ef1ae9 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -345,7 +345,6 @@ extern void user_single_step_siginfo(struct task_struct *tsk, static inline void user_single_step_siginfo(struct task_struct *tsk, struct pt_regs *regs, siginfo_t *info) { - memset(info, 0, sizeof(*info)); info->si_signo = SIGTRAP; } #endif diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index 26c152122a42..4a8841963c2e 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -124,6 +124,7 @@ static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step) { if (step) { siginfo_t info; + clear_siginfo(&info); user_single_step_siginfo(current, regs, &info); force_sig_info(SIGTRAP, &info, current); return; -- cgit v1.2.3 From 31931c93dfe05a76385a443ed28244a50e915a46 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 24 Apr 2018 20:59:47 -0500 Subject: signal: Extend siginfo_layout with SIL_FAULT_{MCEERR|BNDERR|PKUERR} Update the siginfo_layout function and enum siginfo_layout to represent all of the possible field layouts of struct siginfo. This allows the uses of siginfo_layout in um and arm64 where they are testing for SIL_FAULT to be more accurate as this rules out the other cases. Further this allows the switch statements on siginfo_layout to be simpler if perhaps a little more wordy. Making it easier to understand what is actually going on. As SIL_FAULT_BNDERR and SIL_FAULT_PKUERR are never expected to appear in signalfd just treat them as SIL_FAULT. To include them would take 20 extra bytes an pretty much fill up what is left of signalfd_siginfo. Signed-off-by: "Eric W. Biederman" --- fs/signalfd.c | 24 ++++++++++----- include/linux/signal.h | 3 ++ kernel/signal.c | 81 ++++++++++++++++++++++++++++++++++---------------- 3 files changed, 75 insertions(+), 33 deletions(-) (limited to 'include/linux') diff --git a/fs/signalfd.c b/fs/signalfd.c index f652249f59f9..cbb42f77a2bd 100644 --- a/fs/signalfd.c +++ b/fs/signalfd.c @@ -112,19 +112,27 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo, new.ssi_band = kinfo->si_band; new.ssi_fd = kinfo->si_fd; break; + case SIL_FAULT_BNDERR: + case SIL_FAULT_PKUERR: + /* + * Fall through to the SIL_FAULT case. Both SIL_FAULT_BNDERR + * and SIL_FAULT_PKUERR are only generated by faults that + * deliver them synchronously to userspace. In case someone + * injects one of these signals and signalfd catches it treat + * it as SIL_FAULT. + */ case SIL_FAULT: new.ssi_addr = (long) kinfo->si_addr; #ifdef __ARCH_SI_TRAPNO new.ssi_trapno = kinfo->si_trapno; #endif - /* - * Other callers might not initialize the si_lsb field, - * so check explicitly for the right codes here. - */ - if (kinfo->si_signo == SIGBUS && - ((kinfo->si_code == BUS_MCEERR_AR) || - (kinfo->si_code == BUS_MCEERR_AO))) - new.ssi_addr_lsb = (short) kinfo->si_addr_lsb; + break; + case SIL_FAULT_MCEERR: + new.ssi_addr = (long) kinfo->si_addr; +#ifdef __ARCH_SI_TRAPNO + new.ssi_trapno = kinfo->si_trapno; +#endif + new.ssi_addr_lsb = (short) kinfo->si_addr_lsb; break; case SIL_CHLD: new.ssi_pid = kinfo->si_pid; diff --git a/include/linux/signal.h b/include/linux/signal.h index a9bc7e1b077e..3c5200137b24 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -28,6 +28,9 @@ enum siginfo_layout { SIL_TIMER, SIL_POLL, SIL_FAULT, + SIL_FAULT_MCEERR, + SIL_FAULT_BNDERR, + SIL_FAULT_PKUERR, SIL_CHLD, SIL_RT, SIL_SYS, diff --git a/kernel/signal.c b/kernel/signal.c index 376b42f26e6d..8a85da8aaa7c 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2820,8 +2820,19 @@ enum siginfo_layout siginfo_layout(int sig, int si_code) [SIGPOLL] = { NSIGPOLL, SIL_POLL }, [SIGSYS] = { NSIGSYS, SIL_SYS }, }; - if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit)) + if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit)) { layout = filter[sig].layout; + /* Handle the exceptions */ + if ((sig == SIGBUS) && + (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO)) + layout = SIL_FAULT_MCEERR; + else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR)) + layout = SIL_FAULT_BNDERR; +#ifdef SEGV_PKUERR + else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR)) + layout = SIL_FAULT_PKUERR; +#endif + } else if (si_code <= NSIGPOLL) layout = SIL_POLL; } else { @@ -2878,19 +2889,28 @@ int __copy_siginfo_to_user32(struct compat_siginfo __user *to, #ifdef __ARCH_SI_TRAPNO new.si_trapno = from->si_trapno; #endif - if ((from->si_signo == SIGBUS) && - ((from->si_code == BUS_MCEERR_AR) || - (from->si_code == BUS_MCEERR_AO))) - new.si_addr_lsb = from->si_addr_lsb; - - if ((from->si_signo == SIGSEGV) && - (from->si_code == SEGV_BNDERR)) { - new.si_lower = ptr_to_compat(from->si_lower); - new.si_upper = ptr_to_compat(from->si_upper); - } - if ((from->si_signo == SIGSEGV) && - (from->si_code == SEGV_PKUERR)) - new.si_pkey = from->si_pkey; + break; + case SIL_FAULT_MCEERR: + new.si_addr = ptr_to_compat(from->si_addr); +#ifdef __ARCH_SI_TRAPNO + new.si_trapno = from->si_trapno; +#endif + new.si_addr_lsb = from->si_addr_lsb; + break; + case SIL_FAULT_BNDERR: + new.si_addr = ptr_to_compat(from->si_addr); +#ifdef __ARCH_SI_TRAPNO + new.si_trapno = from->si_trapno; +#endif + new.si_lower = ptr_to_compat(from->si_lower); + new.si_upper = ptr_to_compat(from->si_upper); + break; + case SIL_FAULT_PKUERR: + new.si_addr = ptr_to_compat(from->si_addr); +#ifdef __ARCH_SI_TRAPNO + new.si_trapno = from->si_trapno; +#endif + new.si_pkey = from->si_pkey; break; case SIL_CHLD: new.si_pid = from->si_pid; @@ -2956,17 +2976,28 @@ int copy_siginfo_from_user32(struct siginfo *to, #ifdef __ARCH_SI_TRAPNO to->si_trapno = from.si_trapno; #endif - if ((from.si_signo == SIGBUS) && - ((from.si_code == BUS_MCEERR_AR) || - (from.si_code == BUS_MCEERR_AO))) - to->si_addr_lsb = from.si_addr_lsb; - - if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_BNDERR)) { - to->si_lower = compat_ptr(from.si_lower); - to->si_upper = compat_ptr(from.si_upper); - } - if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_PKUERR)) - to->si_pkey = from.si_pkey; + break; + case SIL_FAULT_MCEERR: + to->si_addr = compat_ptr(from.si_addr); +#ifdef __ARCH_SI_TRAPNO + to->si_trapno = from.si_trapno; +#endif + to->si_addr_lsb = from.si_addr_lsb; + break; + case SIL_FAULT_BNDERR: + to->si_addr = compat_ptr(from.si_addr); +#ifdef __ARCH_SI_TRAPNO + to->si_trapno = from.si_trapno; +#endif + to->si_lower = compat_ptr(from.si_lower); + to->si_upper = compat_ptr(from.si_upper); + break; + case SIL_FAULT_PKUERR: + to->si_addr = compat_ptr(from.si_addr); +#ifdef __ARCH_SI_TRAPNO + to->si_trapno = from.si_trapno; +#endif + to->si_pkey = from.si_pkey; break; case SIL_CHLD: to->si_pid = from.si_pid; -- cgit v1.2.3