lkml.org 
[lkml]   [2014]   [Dec]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: perf-probe crash in dwarf_getcfi_elf
On Mon, Dec 29, 2014 at 09:39:18PM -0700, David Ahern wrote:
> Hi Namhyung:
>
> Using perf-probe from top of Linus' tree I get a segfault on both Fedora 16
> and 18 (does not crash on Fedora 20). Command used is:
>
> perf probe -x /lib64/libc-2.14.90.so -a 'malloc size=%di'
>
> git bisect points to:
>
> commit 03d89412981a7681971bc77edba1669595763030
> Author: Namhyung Kim <namhyung@kernel.org>
> Date: Mon Apr 7 16:05:48 2014 +0900
>
> perf probe: Use dwarf_getcfi_elf() instead of dwarf_getcfi()
>

It seems to be related to below commit in elfutils. We might need to
check .eh_frame section has SHT_PROGBITS. Will send a patch soon.

Thanks,
Namhyung


commit 5704c8c4fa717b6e9c2d2e4304dfbc810ad42e4b
Author: Mark Wielaard <mjw@redhat.com>
Date: Tue Jul 2 11:22:35 2013 +0200

getcfi_scn_eh_frame: Don't crash and burn when .eh_frame bits aren't there.

Trying to read non-existing bits sometimes works and normally a sanity
check will fail. But it could also lead to an unexpected crash much later
when trying to use the non-existing data.

Signed-off-by: Mark Wielaard <mjw@redhat.com>

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 700c166..22f8b0c 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,7 @@
+2013-07-02 Mark Wielaard <mjw@redhat.com>
+
+ * dwarf_getcfi_elf.c (getcfi_shdr): Check sh_type == SHT_PROGBITS.
+
2013-06-26 Mark Wielaard <mjw@redhat.com>

* libdw_visit_scopes.c (__libdw_visit_scopes): Don't reject root
diff --git a/libdw/dwarf_getcfi_elf.c b/libdw/dwarf_getcfi_elf.c
index ba00e05..a423ef3 100644
--- a/libdw/dwarf_getcfi_elf.c
+++ b/libdw/dwarf_getcfi_elf.c
@@ -280,8 +280,13 @@ getcfi_shdr (Elf *elf, const GElf_Ehdr *ehdr)
hdr_vaddr = shdr->sh_addr;
}
else if (!strcmp (name, ".eh_frame"))
- return getcfi_scn_eh_frame (elf, ehdr, scn, shdr,
- hdr_scn, hdr_vaddr);
+ {
+ if (shdr->sh_type == SHT_PROGBITS)
+ return getcfi_scn_eh_frame (elf, ehdr, scn, shdr,
+ hdr_scn, hdr_vaddr);
+ else
+ return NULL;
+ }
}
}



> Backtrace at time of crash is:
>
> (gdb) bt
> #0 parse_eh_frame_hdr (hdr=0x0, hdr_size=2596, hdr_vaddr=71788,
> ehdr=0x7fffffffd390, eh_frame_vaddr=
> 0x7fffffffd378, table_entries=0x8808d8, table_encoding=0x8808e0 "") at
> dwarf_getcfi_elf.c:79
> #1 0x000000385f81615a in getcfi_scn_eh_frame (hdr_vaddr=71788,
> hdr_scn=0x8839b0, shdr=0x7fffffffd2f0,
> scn=<optimized out>, ehdr=0x7fffffffd390, elf=0x882b30) at
> dwarf_getcfi_elf.c:231
> #2 getcfi_shdr (ehdr=0x7fffffffd390, elf=0x882b30) at
> dwarf_getcfi_elf.c:283
> #3 dwarf_getcfi_elf (elf=0x882b30) at dwarf_getcfi_elf.c:309
> #4 0x00000000004d5bac in debuginfo__find_probes (pf=0x7fffffffd4f0,
> dbg=Unhandled dwarf expression opcode 0xfa
> ) at util/probe-finder.c:993
> #5 0x00000000004d634a in debuginfo__find_trace_events (dbg=0x880840,
> pev=<optimized out>, tevs=0x880f88,
> max_tevs=<optimized out>) at util/probe-finder.c:1200
> #6 0x00000000004aed6b in try_to_find_probe_trace_events (target=0x881b20
> "/lib64/libpthread-2.14.90.so",
> max_tevs=128, tevs=0x880f88, pev=0x859b30) at util/probe-event.c:482
> #7 convert_to_probe_trace_events (target=0x881b20
> "/lib64/libpthread-2.14.90.so", max_tevs=128, tevs=0x880f88,
> pev=0x859b30) at util/probe-event.c:2356
> #8 add_perf_probe_events (pevs=<optimized out>, npevs=1, max_tevs=128,
> target=
> 0x881b20 "/lib64/libpthread-2.14.90.so", force_add=false) at
> util/probe-event.c:2391
> #9 0x000000000044014f in __cmd_probe (argc=<optimized out>,
> argv=0x7fffffffe2f0, prefix=Unhandled dwarf expression opcode 0xfa
> )
> at builtin-probe.c:488
> #10 0x0000000000440313 in cmd_probe (argc=5, argv=0x7fffffffe2f0,
> prefix=<optimized out>) at builtin-probe.c:506
> #11 0x000000000041d133 in run_builtin (p=0x805680, argc=5,
> argv=0x7fffffffe2f0) at perf.c:341
> #12 0x000000000041c8b2 in handle_internal_command (argv=<optimized out>,
> argc=<optimized out>) at perf.c:400
> #13 run_argv (argv=<optimized out>, argcp=<optimized out>) at perf.c:444
> #14 main (argc=5, argv=0x7fffffffe2f0) at perf.c:559
>
> David
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/


\
 
 \ /
  Last update: 2014-12-30 10:01    [W:0.060 / U:0.128 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site