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SubjectRe: [2.6 patch] acpi/ec.c: fix use-after-free
Date
Applied.

thanks,
-Len


On Wednesday 24 October 2007 13:30, Alexey Starikovskiy wrote:
> Adrian Bunk wrote:
> > On Wed, Oct 24, 2007 at 09:15:18PM +0400, Alexey Starikovskiy wrote:
> >> Adrian,
> >>
> >> commit 30c08574da0ead1a47797ce028218ce5b2de61c7 can not introduce use-after-free.
> >>
> >> Please check...
> >
> >
> > Commit 30c08574da0ead1a47797ce028218ce5b2de61c7 did:
> >
> > <-- snip -->
> >
> > list_for_each_entry(handler, &ec->list, node) {
> > if (query_bit == handler->query_bit) {
> > list_del(&handler->node);
> > kfree(handler);
> > - break;
> > }
> > }
> >
> > <-- snip -->
> >
> >
> > If you look at the definition of list_for_each_entry() in
> > include/linux/list.h:
> >
> > <-- snip -->
> >
> > #define list_for_each_entry(pos, head, member) \
> > for (pos = list_entry((head)->next, typeof(*pos), member); \
> > prefetch(pos->member.next), &pos->member != (head); \
> > pos = list_entry(pos->member.next, typeof(*pos), member))
> > ^^^^^^^^^^^^^^^^
> >
> > <-- snip -->
> >
> >
> > Without the "break", "handler" is being dereferenced after it was freed.
> Yes, found it minute before :(
> Acked, thanks.
> >
> >
> >> Regards,
> >> Alex.
> >> Adrian Bunk wrote:
> >>> This patch fixes a use-after-free introduced by
> >>> commit 30c08574da0ead1a47797ce028218ce5b2de61c7.
> >>>
> >>> Spotted by the Coverity checker.
> >>>
> >>> Signed-off-by: Adrian Bunk <bunk@kernel.org>
> >>>
> >>> ---
> >>> --- linux-2.6/drivers/acpi/ec.c.old 2007-10-23 19:39:47.000000000 +0200
> >>> +++ linux-2.6/drivers/acpi/ec.c 2007-10-23 19:34:55.000000000 +0200
> >>> @@ -434,11 +442,11 @@
> >>> EXPORT_SYMBOL_GPL(acpi_ec_add_query_handler);
> >>>
> >>> void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
> >>> {
> >>> - struct acpi_ec_query_handler *handler;
> >>> + struct acpi_ec_query_handler *handler, *tmp;
> >>> mutex_lock(&ec->lock);
> >>> - list_for_each_entry(handler, &ec->list, node) {
> >>> + list_for_each_entry_safe(handler, tmp, &ec->list, node) {
> >>> if (query_bit == handler->query_bit) {
> >>> list_del(&handler->node);
> >>> kfree(handler);
> >>> }
> >>>
> >
> >
> > cu
> > Adrian
> >
>
> -
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