Re: [PATCH v2] dl-load: add memory barrier before updating the next

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

On 29/03/17 07:59, Maninder Singh wrote:
> This patch adds C11 memory barrier before updating the liblist next.
> 
> Issue Fix: race condition between add_name_to_object  & _dl_name_match_p.
> One threads calling dlopen which further calls add_name_to_object &
> other thread trying to resolve RTLD_LAZY symbols through
> _dl_runtime_resolve which further calls.
> 
> _dl_name_match_p checks if libname->next is valid, then it assumes
> libname->next->name to be valid. Also add_name_to_object initialized
> name first and then sets valid next pointer.
> 
> This patch avoids any reorder of instruction when next is set before
> name to avoid any race.
> 
> Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
> Signed-off-by: Vaneet Narang <v.narang@samsung.com>
> ---
> v1 -> v2 use C11 atomics rather than direct memory barriers
> 
>  elf/dl-load.c |    2 +-
>  elf/dl-misc.c |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)

please report this bug in bugzilla and add the
bug number reference to the changelog according to
https://sourceware.org/glibc/wiki/Contribution%20checklist#Properly_Formatted_GNU_ChangeLog