* [PATCH] libdwfl: fix crash when reading link map
@ 2021-06-10 0:45 Omar Sandoval
2021-06-10 0:51 ` Omar Sandoval
2021-06-10 10:44 ` Dmitry V. Levin
0 siblings, 2 replies; 5+ messages in thread
From: Omar Sandoval @ 2021-06-10 0:45 UTC (permalink / raw)
To: elfutils-devel
From: Omar Sandoval <osandov@fb.com>
When read_addrs() was converted was converted from a nested function to
a normal function, there was a mistake in converting "buffer" from a
closure variable to a parameter: we are checking whether the pointer
argument is NULL, not whether the buffer itself is NULL. This causes a
NULL pointer dereference when we try to use the NULL buffer later.
Fixes: 3bf41d458fb6 ("link_map: Pull read_addrs() into file scope") made
Signed-off-by: Omar Sandoval <osandov@fb.com>
---
libdwfl/ChangeLog | 4 ++++
libdwfl/link_map.c | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index fedf65a4..c57c7708 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,7 @@
+2021-06-09 Omar Sandoval <osandov@fb.com>
+
+ * link_map.c (read_addrs): Fix crash.
+
2021-04-19 Martin Liska <mliska@suse.cz>
* dwfl_frame.c (dwfl_attach_state): Use startswith.
diff --git a/libdwfl/link_map.c b/libdwfl/link_map.c
index 0d8d1c17..1e7d4502 100644
--- a/libdwfl/link_map.c
+++ b/libdwfl/link_map.c
@@ -254,7 +254,7 @@ read_addrs (struct memory_closure *closure,
Dwfl *dwfl = closure->dwfl;
/* Read a new buffer if the old one doesn't cover these words. */
- if (buffer == NULL
+ if (*buffer == NULL
|| vaddr < *read_vaddr
|| vaddr - (*read_vaddr) + nb > *buffer_available)
{
--
2.32.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] libdwfl: fix crash when reading link map
2021-06-10 0:45 [PATCH] libdwfl: fix crash when reading link map Omar Sandoval
@ 2021-06-10 0:51 ` Omar Sandoval
2021-06-10 0:59 ` Érico Nogueira
2021-06-10 10:44 ` Dmitry V. Levin
1 sibling, 1 reply; 5+ messages in thread
From: Omar Sandoval @ 2021-06-10 0:51 UTC (permalink / raw)
To: elfutils-devel
On Wed, Jun 09, 2021 at 05:45:57PM -0700, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>
> When read_addrs() was converted was converted from a nested function to
> a normal function, there was a mistake in converting "buffer" from a
> closure variable to a parameter: we are checking whether the pointer
> argument is NULL, not whether the buffer itself is NULL. This causes a
> NULL pointer dereference when we try to use the NULL buffer later.
>
> Fixes: 3bf41d458fb6 ("link_map: Pull read_addrs() into file scope") made
^^^^
Stray word here, hopefully not too much trouble to fix up when applying.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] libdwfl: fix crash when reading link map
2021-06-10 0:51 ` Omar Sandoval
@ 2021-06-10 0:59 ` Érico Nogueira
2021-06-10 1:02 ` Omar Sandoval
0 siblings, 1 reply; 5+ messages in thread
From: Érico Nogueira @ 2021-06-10 0:59 UTC (permalink / raw)
To: Omar Sandoval, elfutils-devel
Hope you don't mind my nit, then :)
On Wed Jun 9, 2021 at 9:51 PM -03, Omar Sandoval wrote:
> On Wed, Jun 09, 2021 at 05:45:57PM -0700, Omar Sandoval wrote:
> > From: Omar Sandoval <osandov@fb.com>
> >
> > When read_addrs() was converted was converted from a nested function to
^^^^^^^^^^^^^ repeated words
> > a normal function, there was a mistake in converting "buffer" from a
> > closure variable to a parameter: we are checking whether the pointer
> > argument is NULL, not whether the buffer itself is NULL. This causes a
> > NULL pointer dereference when we try to use the NULL buffer later.
> >
> > Fixes: 3bf41d458fb6 ("link_map: Pull read_addrs() into file scope") made
> ^^^^
> Stray word here, hopefully not too much trouble to fix up when applying.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] libdwfl: fix crash when reading link map
2021-06-10 0:59 ` Érico Nogueira
@ 2021-06-10 1:02 ` Omar Sandoval
0 siblings, 0 replies; 5+ messages in thread
From: Omar Sandoval @ 2021-06-10 1:02 UTC (permalink / raw)
To: Érico Nogueira; +Cc: elfutils-devel
On Wed, Jun 09, 2021 at 09:59:06PM -0300, Érico Nogueira wrote:
> Hope you don't mind my nit, then :)
Thanks, that's what I get for sending patches out right before dinner...
> On Wed Jun 9, 2021 at 9:51 PM -03, Omar Sandoval wrote:
> > On Wed, Jun 09, 2021 at 05:45:57PM -0700, Omar Sandoval wrote:
> > > From: Omar Sandoval <osandov@fb.com>
> > >
> > > When read_addrs() was converted was converted from a nested function to
> ^^^^^^^^^^^^^ repeated words
> > > a normal function, there was a mistake in converting "buffer" from a
> > > closure variable to a parameter: we are checking whether the pointer
> > > argument is NULL, not whether the buffer itself is NULL. This causes a
> > > NULL pointer dereference when we try to use the NULL buffer later.
> > >
> > > Fixes: 3bf41d458fb6 ("link_map: Pull read_addrs() into file scope") made
> > ^^^^
> > Stray word here, hopefully not too much trouble to fix up when applying.
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] libdwfl: fix crash when reading link map
2021-06-10 0:45 [PATCH] libdwfl: fix crash when reading link map Omar Sandoval
2021-06-10 0:51 ` Omar Sandoval
@ 2021-06-10 10:44 ` Dmitry V. Levin
1 sibling, 0 replies; 5+ messages in thread
From: Dmitry V. Levin @ 2021-06-10 10:44 UTC (permalink / raw)
To: elfutils-devel
On Wed, Jun 09, 2021 at 05:45:57PM -0700, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>
> When read_addrs() was converted was converted from a nested function to
> a normal function, there was a mistake in converting "buffer" from a
> closure variable to a parameter: we are checking whether the pointer
> argument is NULL, not whether the buffer itself is NULL. This causes a
> NULL pointer dereference when we try to use the NULL buffer later.
>
> Fixes: 3bf41d458fb6 ("link_map: Pull read_addrs() into file scope") made
> Signed-off-by: Omar Sandoval <osandov@fb.com>
Applied, thanks.
--
ldv
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-06-10 0:45 [PATCH] libdwfl: fix crash when reading link map Omar Sandoval
2021-06-10 0:51 ` Omar Sandoval
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2021-06-10 1:02 ` Omar Sandoval
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