When will Linux kernel reset the signal handler for SIGSEGV to SIG_DFL?
If I have set a signal handler for SIGSEGV, whereas a segmentation fault is generated like:
int *a = NULL;
*a = 1;
The handler will be invoked, but this signal handler will be invoked only once. So, I guess Linux kernel will reset the signal handler to SIG_DFL, but when? I want to know the details, so I checked the Linux kernel source code, but couldn't find the clue yet. Please show me the code if you know the details.
c linux-kernel segmentation-fault signal-handling
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381112
add a comment |
If I have set a signal handler for SIGSEGV, whereas a segmentation fault is generated like:
int *a = NULL;
*a = 1;
The handler will be invoked, but this signal handler will be invoked only once. So, I guess Linux kernel will reset the signal handler to SIG_DFL, but when? I want to know the details, so I checked the Linux kernel source code, but couldn't find the clue yet. Please show me the code if you know the details.
c linux-kernel segmentation-fault signal-handling
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381112
add a comment |
If I have set a signal handler for SIGSEGV, whereas a segmentation fault is generated like:
int *a = NULL;
*a = 1;
The handler will be invoked, but this signal handler will be invoked only once. So, I guess Linux kernel will reset the signal handler to SIG_DFL, but when? I want to know the details, so I checked the Linux kernel source code, but couldn't find the clue yet. Please show me the code if you know the details.
c linux-kernel segmentation-fault signal-handling
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381112
If I have set a signal handler for SIGSEGV, whereas a segmentation fault is generated like:
int *a = NULL;
*a = 1;
The handler will be invoked, but this signal handler will be invoked only once. So, I guess Linux kernel will reset the signal handler to SIG_DFL, but when? I want to know the details, so I checked the Linux kernel source code, but couldn't find the clue yet. Please show me the code if you know the details.
c linux-kernel segmentation-fault signal-handling
c linux-kernel segmentation-fault signal-handling
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381112
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381112
edited Nov 13 '18 at 21:59
red0ct
1,30531023
edited Nov 13 '18 at 21:59
red0ct
1,30531023
edited Nov 13 '18 at 21:59
red0ct
1,30531023
1,30531023
asked Nov 13 '18 at 11:22
congcong
381112
asked Nov 13 '18 at 11:22
congcong
381112
asked Nov 13 '18 at 11:22
congcong
381112
381112
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) { write(1,"hn", 2); }
int main()
{
//sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h}, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h,.sa_flags=SA_RESETHAND}, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
}
answered Nov 13 '18 at 15:07
PSkocikPSkocik
32.6k64870
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53279954%2fwhen-will-linux-kernel-reset-the-signal-handler-for-sigsegv-to-sig-dfl%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) { write(1,"hn", 2); }
int main()
{
//sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h}, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h,.sa_flags=SA_RESETHAND}, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
}
answered Nov 13 '18 at 15:07
PSkocikPSkocik
32.6k64870
add a comment |
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) { write(1,"hn", 2); }
int main()
{
//sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h}, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h,.sa_flags=SA_RESETHAND}, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
}
answered Nov 13 '18 at 15:07
PSkocikPSkocik
32.6k64870
add a comment |
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) { write(1,"hn", 2); }
int main()
{
//sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h}, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h,.sa_flags=SA_RESETHAND}, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
}
answered Nov 13 '18 at 15:07
PSkocikPSkocik
32.6k64870
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) { write(1,"hn", 2); }
int main()
{
//sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h}, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction){.sa_handler=h,.sa_flags=SA_RESETHAND}, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
}
answered Nov 13 '18 at 15:07
PSkocikPSkocik
32.6k64870
edited Nov 14 '18 at 2:25
answered Nov 13 '18 at 15:07
PSkocikPSkocik
32.6k64870
answered Nov 13 '18 at 15:07
PSkocikPSkocik
32.6k64870
answered Nov 13 '18 at 15:07
PSkocikPSkocik
32.6k64870
32.6k64870
add a comment |
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53279954%2fwhen-will-linux-kernel-reset-the-signal-handler-for-sigsegv-to-sig-dfl%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
