Re: [PATCH 1/2] symtab-reader: Remove an over-agressive assertion

[Dodji Seketeli <dodji@redhat.com>]

Giuliano Procida via Libabigail <libabigail@sourceware.org> a écrit:

> Hi.
>
> On Mon, 7 Feb 2022 at 11:10, Dodji Seketeli <dodji@redhat.com> wrote:
>>
>>
>> In symtab::load, the symtab reader walks the symbol table and records
>> each relation "symbol <-> address".
>> So, the relation "foo <-> address-of-foo" is going to be recorded.
>> The relation "foo.cfi <-> address-of-foo.cfi" is going to be recorded
>> as well.
>>
>> But then, because the symbol foo.cfi has a special meaning, in the
>> realm of "control flow integrity", the relation "foo.cfi <->
>> address-of-foo.cfi" (as well as all the *.cfi <-> address-of*.cfi
>> relations) is going to be recorded (again but) in a particular way by
>> calling symtab::add_alternative_address_lookups.
>>
>> The problem is that in, symtab::add_alternative_address_lookups there
>> is an assert that (wrongly) assumes that the relation foo.cfi <->
>> address-of-foo.cfi is being seen for the first time.  This is wrong
>> because the loop in symtab::load that records all the "symbol <->
>> address" relations has seen and recorded this foo.cfi <->
>> address-of-foo.cfi relation once already.
>>
>> This patch removes that assert so that the kernel referred to in the bug
>> report of PR26646, as mentioned in
>> https://sourceware.org/bugzilla/show_bug.cgi?id=26646#c5, can be
>> processed by abidw without crashing.
>>
>>         * src/abg-symtab-reader.cc
>>         (symtab::add_alternative_address_lookups): Remove over-aggressive
>>         assert.
>>
>> Signed-off-by: Dodji Seketeli <dodji@redhat.com>
>
> Reviewed-by: Giuliano Procida <gprocida@google.com>
>
> I didn't see a better solution and you've written up a proper analysis
> in the commit message. Thanks!

Thanks!

Applied to master.

[...]

Cheers,

-- 
		Dodji