* Commit: Fix seg-fault in dwarf.c:process_debug_info
@ 2024-04-03 10:19 Nick Clifton
2024-04-11 23:36 ` Fix null pointer dereference in process_debug_info() Alan Modra
0 siblings, 1 reply; 2+ messages in thread
From: Nick Clifton @ 2024-04-03 10:19 UTC (permalink / raw)
To: binutils
Hi Guys,
I recently discovered that I could not examine the debug info in the
libc shared library without running into a null-pointer dereference:
$ readelf -wi /lib64/libc.so.6
[...]
Segmentation fault (core dumped)
The issue is code in process_debug_info() which checks for a negative
rnglists_base without first testing to make sure that a value exists.
So I am applying the patch below as an obvious fix for the problem.
Cheers
Nick
diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index 92a07e00e9b..ce508d0315f 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -4248,14 +4248,17 @@ process_debug_info (struct dwarf_section * section,
compunit.cu_version,
debug_info_p);
- /* This check was in place before, keep it. */
- stemp = debug_info_p->rnglists_base;
- if (stemp < 0)
+ if (debug_info_p)
{
- warn (_("CU @ %#" PRIx64 " has has a negative rnglists_base "
- "value of %#" PRIx64 " - treating as zero"),
- debug_info_p->cu_offset, stemp);
- debug_info_p->rnglists_base = 0;
+ /* This check was in place before, keep it. */
+ stemp = debug_info_p->rnglists_base;
+ if (stemp < 0)
+ {
+ warn (_("CU @ %#" PRIx64 " has has a negative rnglists_base "
+ "value of %#" PRIx64 " - treating as zero"),
+ debug_info_p->cu_offset, stemp);
+ debug_info_p->rnglists_base = 0;
+ }
}
}
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Fix null pointer dereference in process_debug_info()
2024-04-03 10:19 Commit: Fix seg-fault in dwarf.c:process_debug_info Nick Clifton
@ 2024-04-11 23:36 ` Alan Modra
0 siblings, 0 replies; 2+ messages in thread
From: Alan Modra @ 2024-04-11 23:36 UTC (permalink / raw)
To: binutils
read_bases has a potential null-pointer deref too, and without a
debug_info_p there isn't any point in calling read_bases.
* dwarf.c (process_debug_info): Don't call read_bases when
debug_info_p is NULL.
diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index ce508d0315f..3ce79f4e5d1 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -4236,7 +4236,7 @@ process_debug_info (struct dwarf_section * section,
Only needed for the top DIE on DWARFv5+.
No simiar treatment for loclists_base because there should
be no loclist attributes in top DIE. */
- if (compunit.cu_version >= 5 && level == 0)
+ if (debug_info_p && compunit.cu_version >= 5 && level == 0)
{
int64_t stemp;
@@ -4248,17 +4248,14 @@ process_debug_info (struct dwarf_section * section,
compunit.cu_version,
debug_info_p);
- if (debug_info_p)
+ /* This check was in place before, keep it. */
+ stemp = debug_info_p->rnglists_base;
+ if (stemp < 0)
{
- /* This check was in place before, keep it. */
- stemp = debug_info_p->rnglists_base;
- if (stemp < 0)
- {
- warn (_("CU @ %#" PRIx64 " has has a negative rnglists_base "
- "value of %#" PRIx64 " - treating as zero"),
- debug_info_p->cu_offset, stemp);
- debug_info_p->rnglists_base = 0;
- }
+ warn (_("CU @ %#" PRIx64 " has has a negative rnglists_base "
+ "value of %#" PRIx64 " - treating as zero"),
+ debug_info_p->cu_offset, stemp);
+ debug_info_p->rnglists_base = 0;
}
}
--
Alan Modra
Australia Development Lab, IBM
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2024-04-11 23:36 ` Fix null pointer dereference in process_debug_info() Alan Modra
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