From 12ca42c237756182aad8ab04654c952765cb9061 Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Fri, 16 May 2025 17:07:39 -0700 Subject: alloc_tag: allocate percpu counters for module tags dynamically When a module gets unloaded it checks whether any of its tags are still in use and if so, we keep the memory containing module's allocation tags alive until all tags are unused. However percpu counters referenced by the tags are freed by free_module(). This will lead to UAF if the memory allocated by a module is accessed after module was unloaded. To fix this we allocate percpu counters for module allocation tags dynamically and we keep it alive for tags which are still in use after module unloading. This also removes the requirement of a larger PERCPU_MODULE_RESERVE when memory allocation profiling is enabled because percpu memory for counters does not need to be reserved anymore. Link: https://lkml.kernel.org/r/20250517000739.5930-1-surenb@google.com Fixes: 0db6f8d7820a ("alloc_tag: load module tags into separate contiguous memory") Signed-off-by: Suren Baghdasaryan Reported-by: David Wang <00107082@163.com> Closes: https://lore.kernel.org/all/20250516131246.6244-1-00107082@163.com/ Tested-by: David Wang <00107082@163.com> Cc: Christoph Lameter (Ampere) Cc: Dennis Zhou Cc: Kent Overstreet Cc: Pasha Tatashin Cc: Tejun Heo Cc: Signed-off-by: Andrew Morton --- include/linux/percpu.h | 4 ---- 1 file changed, 4 deletions(-) (limited to 'include/linux/percpu.h') diff --git a/include/linux/percpu.h b/include/linux/percpu.h index 52b5ea663b9f..85bf8dd9f087 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -15,11 +15,7 @@ /* enough to cover all DEFINE_PER_CPUs in modules */ #ifdef CONFIG_MODULES -#ifdef CONFIG_MEM_ALLOC_PROFILING -#define PERCPU_MODULE_RESERVE (8 << 13) -#else #define PERCPU_MODULE_RESERVE (8 << 10) -#endif #else #define PERCPU_MODULE_RESERVE 0 #endif -- cgit v1.2.3