module: Extend the preempt disabled section in dereference_symbol_descriptor().

dereference_symbol_descriptor() needs to obtain the module pointer
belonging to pointer in order to resolve that pointer.
The returned mod pointer is obtained under RCU-sched/ preempt_disable()
guarantees and needs to be used within this section to ensure that the
module is not removed in the meantime.

Extend the preempt_disable() section to also cover
dereference_module_function_descriptor().

Fixes: 04b8eb7a4ccd9 ("symbol lookup: introduce dereference_symbol_descriptor()")
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Helge Deller <deller@gmx.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20250108090457.512198-2-bigeasy@linutronix.de
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>

diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index c3f075e8f60cb673e452e7e35c0b3a303597cdbe..1c6a6c1704d8d059ac759d4a8652a86acaa605fe 100644 (file)
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -57,10 +57,10 @@ static inline void *dereference_symbol_descriptor(void *ptr)
 
        preempt_disable();
        mod = __module_address((unsigned long)ptr);
-       preempt_enable();
 
        if (mod)
                ptr = dereference_module_function_descriptor(mod, ptr);
+       preempt_enable();
 #endif
        return ptr;
 }