[Crash-utility] Re: [PATCH] Fix the segfault issue caused by "dis -s" command

I did some tests on the vmcore with Rust enabled, and found that the "dis -s" command may cause a segfault: crash> dis -s _RNvCscb18lrEyTSA_10rust_panic10area_in_hp Enable debuginfod for this session? (y or [n]) FILE: rust_panic.rs LINE: 22 Segmentation fault (core dumped) ./crash /home/lijiang/src/rust/6.16.3-vmcore-rust/vmlinux /home/lijiang/src/rust/6.16.3-vmcore-rust/vmcore gdb calltrace: (gdb) bt #0 decimal (s=0x0, count=count@entry=0) at tools.c:1113 #1 0x00000000008eea96 in list_source_code (req=0x1081860 <shared_bufs>, count_entered=0) at kernel.c:1578 #2 cmd_dis () at kernel.c:2052 #3 0x000000000086b468 in exec_command () at main.c:893 #4 0x000000000086b6aa in main_loop () at main.c:840 #5 0x00000000006b950c in captured_main (data=data@entry=0x7ffe049a3bd0) at main.c:1374 #6 gdb_main (args=args@entry=0x7ffe049a3c10) at main.c:1407 #7 0x00000000006b9579 in gdb_main_entry (argc=2, argv=argv@entry=0x7ffe049a3db8) at main.c:1434 #8 0x000000000090529e in gdb_main_loop (argc=<optimized out>, argc@entry=3, argv=argv@entry=0x7ffe049a3db8) at gdb_interface.c:81 #9 0x0000000000438344 in main (argc=3, argv=0x7ffe049a3db8) at main.c:721 (gdb) This is because the decimal() tried to dereference a NULL pointer in the list_source_code() path, when the source code is not available. Given that, let's add a check to fix such cases. With the patch: crash> dis -s _RNvCscb18lrEyTSA_10rust_panic10area_in_hp Enable debuginfod for this session? (y or [n]) FILE: rust_panic.rs LINE: 22 dis: _RNvCscb18lrEyTSA_10rust_panic10area_in_hp: source code is not available crash> Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; --- tools.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools.c b/tools.c index c9305bef7c9c..a9ad18d520d9 100644 --- a/tools.c +++ b/tools.c @@ -1110,7 +1110,7 @@ decimal(char *s, int count) } else cnt = count; - for (p = &s[0], digits = 0; *p; p++) { + for (p = &s[0], digits = 0; p && *p; p++) { switch(*p) { case '0': -- 2.50.1