Re: [PATCH] livepatch: RCU protect struct klp_func all the time when used in klp_ftrace_handler()
On Wed, 18 Feb 2015, Petr Mladek wrote: > func->new_func has been accessed after rcu_read_unlock() in > klp_ftrace_handler() > and therefore the access was not protected. > > Signed-off-by: Petr Mladek Applied to for-3.20/upstream-fixes, thanks. -- Jiri Kosina SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] livepatch: RCU protect struct klp_func all the time when used in klp_ftrace_handler()
On Sat, Feb 21, 2015 at 12:29:30AM +0100, Jiri Kosina wrote: > On Wed, 18 Feb 2015, Petr Mladek wrote: > > > func->new_func has been accessed after rcu_read_unlock() in > > klp_ftrace_handler() > > and therefore the access was not protected. > > > > Signed-off-by: Petr Mladek > > --- > > kernel/livepatch/core.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > > index ff7f47d026ac..cde66192e20e 100644 > > --- a/kernel/livepatch/core.c > > +++ b/kernel/livepatch/core.c > > @@ -314,12 +314,12 @@ static void notrace klp_ftrace_handler(unsigned long > > ip, > > rcu_read_lock(); > > func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, > > stack_node); > > - rcu_read_unlock(); > > - > > if (WARN_ON_ONCE(!func)) > > - return; > > + goto unlock; > > > > klp_arch_set_pc(regs, (unsigned long)func->new_func); > > +unlock: > > + rcu_read_unlock(); > > This can't hurt, even though the only scenario where this could in theory > trigger as a bug (module removal) is non-issue now. > > But I'd like to take it nevertheless ... Seth, Josh? Acked-by: Josh Poimboeuf -- Josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] livepatch: RCU protect struct klp_func all the time when used in klp_ftrace_handler()
On Wed, 18 Feb 2015, Petr Mladek wrote: > func->new_func has been accessed after rcu_read_unlock() in > klp_ftrace_handler() > and therefore the access was not protected. > > Signed-off-by: Petr Mladek > --- > kernel/livepatch/core.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > index ff7f47d026ac..cde66192e20e 100644 > --- a/kernel/livepatch/core.c > +++ b/kernel/livepatch/core.c > @@ -314,12 +314,12 @@ static void notrace klp_ftrace_handler(unsigned long ip, > rcu_read_lock(); > func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, > stack_node); > - rcu_read_unlock(); > - > if (WARN_ON_ONCE(!func)) > - return; > + goto unlock; > > klp_arch_set_pc(regs, (unsigned long)func->new_func); > +unlock: > + rcu_read_unlock(); This can't hurt, even though the only scenario where this could in theory trigger as a bug (module removal) is non-issue now. But I'd like to take it nevertheless ... Seth, Josh? Thanks, -- Jiri Kosina SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
