diff options
Diffstat (limited to 'linker')
| -rw-r--r-- | linker/debugger.cpp | 47 |
1 files changed, 28 insertions, 19 deletions
diff --git a/linker/debugger.cpp b/linker/debugger.cpp index b7e84acb5..d4c7928f5 100644 --- a/linker/debugger.cpp +++ b/linker/debugger.cpp @@ -39,6 +39,7 @@ #include <sys/mman.h> #include <sys/prctl.h> #include <sys/socket.h> +#include <sys/syscall.h> #include <sys/un.h> #include <unistd.h> @@ -61,7 +62,9 @@ enum debugger_action_t { DEBUGGER_ACTION_DUMP_BACKTRACE, }; -/* message sent over the socket */ +// Message sent over the socket. +// NOTE: Any changes to this structure must also be reflected in +// system/core/include/cutils/debugger.h. struct __attribute__((packed)) debugger_msg_t { int32_t action; pid_t tid; @@ -267,26 +270,32 @@ static void debuggerd_signal_handler(int signal_number, siginfo_t* info, void*) send_debuggerd_packet(info); - // Remove our net so we fault for real when we return. + // We need to return from the signal handler so that debuggerd can dump the + // thread that crashed, but returning here does not guarantee that the signal + // will be thrown again, even for SIGSEGV and friends, since the signal could + // have been sent manually. Resend the signal with rt_tgsigqueueinfo(2) to + // preserve the SA_SIGINFO contents. signal(signal_number, SIG_DFL); - // These signals are not re-thrown when we resume. This means that - // crashing due to (say) SIGABRT doesn't work the way you'd expect it - // to. We work around this by throwing them manually. We don't want - // to do this for *all* signals because it'll screw up the si_addr for - // faults like SIGSEGV. It does screw up the si_code, which is why we - // passed that to debuggerd above. - switch (signal_number) { - case SIGABRT: - case SIGFPE: -#if defined(SIGSTKFLT) - case SIGSTKFLT: -#endif - case SIGTRAP: - tgkill(getpid(), gettid(), signal_number); - break; - default: // SIGILL, SIGBUS, SIGSEGV - break; + struct siginfo si; + if (!info) { + memset(&si, 0, sizeof(si)); + si.si_code = SI_USER; + si.si_pid = getpid(); + si.si_uid = getuid(); + info = &si; + } else if (info->si_code >= 0 || info->si_code == SI_TKILL) { + // rt_tgsigqueueinfo(2)'s documentation appears to be incorrect on kernels + // that contain commit 66dd34a (3.9+). The manpage claims to only allow + // negative si_code values that are not SI_TKILL, but 66dd34a changed the + // check to allow all si_code values in calls coming from inside the house. + } + + int rc = syscall(SYS_rt_tgsigqueueinfo, getpid(), gettid(), signal_number, info); + if (rc != 0) { + __libc_format_log(ANDROID_LOG_FATAL, "libc", "failed to resend signal during crash: %s", + strerror(errno)); + _exit(0); } } |