From: Simon Marchi <simon.marchi@polymtl.ca>
To: Rian Hunter <rian@thelig.ht>
Cc: gdb-patches@sourceware.org
Subject: Re: fix invalid memory references in gdb/jit.c
Date: Tue, 07 Aug 2018 22:04:00 -0000 [thread overview]
Message-ID: <a85a7f174b56fd5600720812d5709ea0@polymtl.ca> (raw)
In-Reply-To: <8ff4437eb869559c2f917dcb49d3cacd@thelig.ht>
On 2018-08-06 21:05, Rian Hunter wrote:
> These patches fix the case where calling block_open() non-1 amount of
> times causes seg faults. This is when using the custom jit reader API.
Hi Rian,
Thanks for the patch. Would it be possible to create a test case or
enhance an existing one to illustrate the problem (and prevent it coming
back)? I haven't looked in details, but
gdb/testsuite/gdb.base/jit-reader.exp looks promising.
Also, could you please try sending your patch using git-send-email next
time? It helps a lot when applying it.
> diff --git a/gdb/jit.c b/gdb/jit.c
> index e6b3cc25ca..78295f0dc2 100644
> --- a/gdb/jit.c
> +++ b/gdb/jit.c
> @@ -684,8 +684,11 @@ finalize_symtab (struct gdb_symtab *stab, struct
> objfile *objfile)
> /* (begin, end) will contain the PC range this entire blockvector
> spans. */
> BLOCKVECTOR_MAP (bv) = NULL;
> - begin = stab->blocks->begin;
> - end = stab->blocks->end;
> + if (stab->blocks)
if (stab->blocks != nullptr)
> + {
> + begin = stab->blocks->begin;
> + end = stab->blocks->end;
> + }
> BLOCKVECTOR_NBLOCKS (bv) = actual_nblocks;
>
> /* First run over all the gdb_block objects, creating a real block
> @@ -780,7 +783,8 @@ finalize_symtab (struct gdb_symtab *stab, struct
> objfile *objfile)
>
> for (gdb_block_iter = stab->blocks, gdb_block_iter_tmp =
> gdb_block_iter->next;
> gdb_block_iter;
> - gdb_block_iter = gdb_block_iter_tmp)
> + gdb_block_iter = gdb_block_iter_tmp,
> + gdb_block_iter_tmp = (gdb_block_iter ? gdb_block_iter->next :
> NULL))
> {
> xfree ((void *) gdb_block_iter->name);
> xfree (gdb_block_iter);
I'm not sure I see how this helps when stab->blocks is NULL. This is
how the look initialization is done:
gdb_block_iter = stab->blocks, gdb_block_iter_tmp =
gdb_block_iter->next
If stab->blocks is null, gdb_block_iter will be too, and
"gdb_block_iter->next" will segfault, won't it?
Simon
prev parent reply other threads:[~2018-08-07 22:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-07 1:06 Rian Hunter
2018-08-07 22:04 ` Simon Marchi [this message]
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