Re: [PATCH v3 01/28] module: Extend the preempt disabled section in dereference_symbol_descriptor().
From: Helge Deller <deller@gmx.de>
Date: 2025-01-08 09:55:45
Also in:
linux-modules, lkml
On 1/8/25 10:04, Sebastian Andrzej Siewior wrote:
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 <redacted>
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 <redacted>
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>Nice catch. Acked-by: Helge Deller <deller@gmx.de> This patch really should be backported. Can you add a Cc: stable tag? Helge
quoted hunk ↗ jump to hunk
--- include/linux/kallsyms.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index c3f075e8f60cb..1c6a6c1704d8d 100644 --- 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; }