https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95188
Bug ID: 95188
Summary: analyzer-unsafe-call-within-signal-handler shows wrong
statement for signal registration event
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: mark at gcc dot gnu.org
Target Milestone: ---
Reproducer:
wget https://sourceware.org/ftp/bzip2/bzip2-1.0.8.tar.gz
tar zxf bzip2-1.0.8.tar.gz
cd bzip2-1.0.8/
gcc -g -O2 -fanalyzer -c bzip2.c
In function ‘showFileNames.part.0’:
bzip2.c:677:4: warning: call to ‘fprintf’ from within signal handler [CWE-479]
[-Wanalyzer-unsafe-call-within-signal-handler]
677 | fprintf (
| ^~~~~~~~~
678 | stderr,
| ~~~~~~~
679 | "\tInput file = %s, output file = %s\n",
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
680 | inName, outName
| ~~~~~~~~~~~~~~~
681 | );
| ~
‘main’: events 1-2
|
| 1776 | IntNative main ( IntNative argc, Char *argv[] )
| | ^~~~
| | |
| | (1) entry to ‘main’
|......
| 1792 | smallMode = False;
| | ~~~~~~~~~
| | |
| | (2) registering ‘mySIGSEGVorSIGBUScatcher’ as signal handler
|
event 3
|
|cc1:
| (3): later on, when the signal is delivered to the process
|
+--> ‘mySIGSEGVorSIGBUScatcher’: events 4-5
|
| 676 | if (noisy)
| | ~
| | |
| | (5) following ‘true’ branch...
|......
| 816 | void mySIGSEGVorSIGBUScatcher ( IntNative n )
| | ^~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (4) entry to ‘mySIGSEGVorSIGBUScatcher’
|
‘mySIGSEGVorSIGBUScatcher’: event 6
|
|cc1:
| (6): ...to here
|
‘mySIGSEGVorSIGBUScatcher’: event 7
|
|cc1:
| (7): calling ‘showFileNames.part.0’ from
‘mySIGSEGVorSIGBUScatcher’
|
+--> ‘showFileNames.part.0’: events 8-9
|
| 674 | void showFileNames ( void )
| | ^~~~~~~~~~~~~
| | |
| | (8) entry to ‘showFileNames.part.0’
|......
| 677 | fprintf (
| | ~~~~~~~~~
| | |
| | (9) call to ‘fprintf’ from within signal handler
| 678 | stderr,
| | ~~~~~~~
| 679 | "\tInput file = %s, output file = %s\n",
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| 680 | inName, outName
| | ~~~~~~~~~~~~~~~
| 681 | );
| | ~
|
Note that the signal handler registration points to the wrong instruction:
| 1792 | smallMode = False;
| | ~~~~~~~~~
| | |
| | (2) registering ‘mySIGSEGVorSIGBUScatcher’ as signal handler
A workaround is to add -fanalyzer-fine-grained, then it does show to correct
signal registration event:
| 1808 | signal (SIGSEGV, mySIGSEGVorSIGBUScatcher);
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (2) registering ‘mySIGSEGVorSIGBUScatcher’ as signal handler
