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Code Issues Releases Wiki Activity

change SIGSEGV handler to use SA_SIGINFO to get context information, and

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get a stack dump too
This commit is contained in:
Greg Alexander 2019-07-28 22:41:03 -04:00
parent 62b119e07f
commit d7bd00fc2b
1 changed files with 74 additions and 5 deletions
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79
dropbear/svr-main.c
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@ -30,10 +30,12 @@
#include "runopts.h"
#include "dbrandom.h"
#include "crypto_desc.h"
#include <unwind.h>
#include <dlfcn.h>
#include <sys/ucontext.h>
static size_t listensockets(int *sock, size_t sockcount, int *maxfd);
static void sigchld_handler(int dummy);
static void sigsegv_handler(int);
static void sigintterm_handler(int fish);
#if INETD_MODE
static void main_inetd(void);
@ -193,7 +195,9 @@ static void main_noinetd() {
}
}
fprintf(stderr,"server select in\n");
val = select(maxsock+1, &fds, NULL, NULL, NULL);
fprintf(stderr,"server select out (%d)\n", (int)val);
if (ses.exitflag) {
unlink(svr_opts.pidfile);
@ -345,7 +349,9 @@ static void sigchld_handler(int UNUSED(unused)) {
const int saved_errno = errno;
fprintf(stderr,"sigchld\n");
while(waitpid(-1, NULL, WNOHANG) > 0) {}
fprintf(stderr,"sigchld return from waitpid\n");
sa_chld.sa_handler = sigchld_handler;
sa_chld.sa_flags = SA_NOCLDSTOP;
@ -356,10 +362,64 @@ static void sigchld_handler(int UNUSED(unused)) {
errno = saved_errno;
}
static volatile uintptr_t stack[16];
static volatile int stack_count;
static _Unwind_Reason_Code unwindCallback(struct _Unwind_Context* context, void* arg)
{
uintptr_t pc = _Unwind_GetIP(context);
if (pc) {
if (stack_count >= sizeof stack / sizeof stack[0]) {
return _URC_END_OF_STACK;
} else {
stack[stack_count++] = pc;
}
}
return _URC_NO_REASON;
}
static void
dump_sym(uintptr_t addr)
{
char* symbol = "";
Dl_info info;
if (dladdr((void*)addr, &info)) {
if (info.dli_sname) {
fprintf(stderr, "%016llX (%s=%016llX)\n", (unsigned long long)addr, info.dli_sname, (unsigned long long)info.dli_saddr);
} else if (info.dli_fname) {
fprintf(stderr, "%016llX (f %s=%016llX)\n", (unsigned long long)addr, info.dli_fname, (unsigned long long)info.dli_fbase);
} else {
fprintf(stderr, "%016llX\n", (unsigned long long)addr);
}
} else {
fprintf(stderr, "%016llX (no dladdr)\n", (unsigned long long)addr);
}
}
static void backtrace(void) {
int i;
stack_count = 0;
_Unwind_Backtrace(unwindCallback, NULL);
fprintf(stderr, "stack:\n");
for (i = 0; i < stack_count; i++) {
dump_sym(stack[i]);
}
}
/* catch any segvs */
static void sigsegv_handler(int UNUSED(unused)) {
static void sigsegv_handler(int sig, siginfo_t *info, void *ucontext) {
struct sigcontext *ctx = &((ucontext_t *)ucontext)->uc_mcontext;
fprintf(stderr, "Aiee, segfault! You should probably report "
"this as a bug to the developer\n");
#if defined(__aarch64__)
fprintf(stderr,"sp=%016llX\n", (unsigned long long)ctx->sp);
fprintf(stderr,"fault_address=%016llX\n", (unsigned long long)ctx->fault_address);
fprintf(stderr, "pc=");
dump_sym(ctx->pc);
{ int i; for (i = 0; i < 31; i++) { fprintf(stderr,"r%d=%016llX\n", i, (unsigned long long)ctx->regs[i]); } }
#else
fprintf(stderr,"not aarch64\n");
#endif
backtrace();
_exit(EXIT_FAILURE);
}
@ -395,9 +455,18 @@ static void commonsetup() {
if (sigaction(SIGCHLD, &sa_chld, NULL) < 0) {
dropbear_exit("signal() error");
}
if (signal(SIGSEGV, sigsegv_handler) == SIG_ERR) {
dropbear_exit("signal() error");
}
{
struct sigaction sa;
sa.sa_sigaction = sigsegv_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART|SA_SIGINFO;
sigaction(SIGSEGV, &sa, NULL);
}
// if (signal(SIGSEGV, sigsegv_handler) == SIG_ERR) {
// dropbear_exit("signal() error");
// }
crypto_init();