| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <44d4cf82-982c-455b-85c1-138e8c37cc8f@kylinos.cn> Date: Mon, 22 Dec 2025 17:37:19 +0800 From: Enze Li <lienze@...inos.cn> To: yuanlinyu <yuanlinyu@...or.com>, Huacai Chen <chenhuacai@...nel.org> Cc: Alexander Potapenko <glider@...gle.com>, Marco Elver <elver@...gle.com>, Dmitry Vyukov <dvyukov@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, WANG Xuerui <kernel@...0n.name>, "kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "loongarch@...ts.linux.dev" <loongarch@...ts.linux.dev>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "enze.li@....com" <enze.li@....com> Subject: Re: [PATCH v2 1/2] LoongArch: kfence: avoid use CONFIG_KFENCE_NUM_OBJECTS On 12/22/25 5:16 PM, yuanlinyu wrote: >> From: Enze Li <lienze@...inos.cn> >> Sent: Saturday, December 20, 2025 1:44 PM >> To: Huacai Chen <chenhuacai@...nel.org>; yuanlinyu <yuanlinyu@...or.com> >> Cc: Alexander Potapenko <glider@...gle.com>; Marco Elver >> <elver@...gle.com>; Dmitry Vyukov <dvyukov@...gle.com>; Andrew Morton >> <akpm@...ux-foundation.org>; WANG Xuerui <kernel@...0n.name>; >> kasan-dev@...glegroups.com; linux-mm@...ck.org; loongarch@...ts.linux.dev; >> linux-kernel@...r.kernel.org; enze.li@....com >> Subject: Re: [PATCH v2 1/2] LoongArch: kfence: avoid use >> CONFIG_KFENCE_NUM_OBJECTS >> >> On 2025/12/19 10:13, Huacai Chen wrote: >>> Hi, Enze, >>> >>> On Thu, Dec 18, 2025 at 2:39 PM yuan linyu <yuanlinyu@...or.com> wrote: >>>> >>>> use common kfence macro KFENCE_POOL_SIZE for KFENCE_AREA_SIZE >>>> definition >>>> >>>> Signed-off-by: yuan linyu <yuanlinyu@...or.com> >>>> --- >>>> arch/loongarch/include/asm/pgtable.h | 3 ++- >>>> 1 file changed, 2 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/arch/loongarch/include/asm/pgtable.h >>>> b/arch/loongarch/include/asm/pgtable.h >>>> index f41a648a3d9e..e9966c9f844f 100644 >>>> --- a/arch/loongarch/include/asm/pgtable.h >>>> +++ b/arch/loongarch/include/asm/pgtable.h >>>> @@ -10,6 +10,7 @@ >>>> #define _ASM_PGTABLE_H >>>> >>>> #include <linux/compiler.h> >>>> +#include <linux/kfence.h> >>>> #include <asm/addrspace.h> >>>> #include <asm/asm.h> >>>> #include <asm/page.h> >>>> @@ -96,7 +97,7 @@ extern unsigned long empty_zero_page[PAGE_SIZE / >> sizeof(unsigned long)]; >>>> #define MODULES_END (MODULES_VADDR + SZ_256M) >>>> >>>> #ifdef CONFIG_KFENCE >>>> -#define KFENCE_AREA_SIZE (((CONFIG_KFENCE_NUM_OBJECTS + 1) >> * 2 + 2) * PAGE_SIZE) >>>> +#define KFENCE_AREA_SIZE (KFENCE_POOL_SIZE + (2 * >> PAGE_SIZE)) >>> Can you remember why you didn't use KFENCE_POOL_SIZE at the first place? >> >> I don't recall the exact reason off the top of my head, but I believe it was due to >> complex dependency issues with the header files where KFENCE_POOL_SIZE is >> defined. To avoid those complications, we likely opted to use >> KFENCE_NUM_OBJECTS directly. >> >> I checked out the code at commit >> (6ad3df56bb199134800933df2afcd7df3b03ef33 "LoongArch: Add KFENCE >> (Kernel >> Electric-Fence) support") and encountered the following errors when compiling >> with this patch applied. >> >> 8<------------------------------------------------------ >> CC arch/loongarch/kernel/asm-offsets.s >> In file included from ./arch/loongarch/include/asm/pgtable.h:13, >> from ./include/linux/pgtable.h:6, >> from ./include/linux/mm.h:29, >> from arch/loongarch/kernel/asm-offsets.c:9: >> ./include/linux/kfence.h:93:35: warning: 'struct kmem_cache' declared inside >> parameter list will n ot be visible outside of this definition or declaration >> 93 | void kfence_shutdown_cache(struct kmem_cache *s); >> | ^~~~~~~~~~ >> ./include/linux/kfence.h:99:29: warning: 'struct kmem_cache' declared inside >> parameter list will n ot be visible outside of this definition or declaration >> 99 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); >> | ^~~~~~~~~~ >> ./include/linux/kfence.h:117:50: warning: 'struct kmem_cache' declared inside >> parameter list will not be visible outside of this definition or declaration >> 117 | static __always_inline void *kfence_alloc(struct kmem_cache *s, size_t >> size, gfp_t flags) >> | >> ^~~~~~~~~~ >> ./include/linux/kfence.h: In function 'kfence_alloc': >> ./include/linux/kfence.h:128:31: error: passing argument 1 of '__kfence_alloc' >> from incompatible p ointer type [-Wincompatible-pointer-types] >> 128 | return __kfence_alloc(s, size, flags); >> | ^ >> | | >> | struct kmem_cache * >> ./include/linux/kfence.h:99:41: note: expected 'struct kmem_cache *' but >> argument is of type 'stru ct kmem_cache *' >> 99 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); >> | ~~~~~~~~~~~~~~~~~~~^ >> ------------------------------------------------------>8 >> >> Similarly, after applying this patch to the latest code >> (dd9b004b7ff3289fb7bae35130c0a5c0537266af "Merge tag 'trace-v6.19-rc1'") >> from the master branch of the Linux repository and enabling KFENCE, I >> encountered the following compilation errors. >> >> 8<------------------------------------------------------ >> CC arch/loongarch/kernel/asm-offsets.s >> In file included from ./arch/loongarch/include/asm/pgtable.h:13, >> from ./include/linux/pgtable.h:6, >> from ./include/linux/mm.h:31, >> from arch/loongarch/kernel/asm-offsets.c:11: >> ./include/linux/kfence.h:97:35: warning: 'struct kmem_cache' declared inside >> parameter list will n ot be visible outside of this definition or declaration >> 97 | void kfence_shutdown_cache(struct kmem_cache *s); >> | ^~~~~~~~~~ >> ./include/linux/kfence.h:103:29: warning: 'struct kmem_cache' declared inside >> parameter list will not be visible outside of this definition or declaration >> 103 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); >> | ^~~~~~~~~~ >> ./include/linux/kfence.h:121:50: warning: 'struct kmem_cache' declared inside >> parameter list will not be visible outside of this definition or declaration >> 121 | static __always_inline void *kfence_alloc(struct kmem_cache *s, size_t >> size, gfp_t flags) >> | >> ^~~~~~~~~~ >> ./include/linux/kfence.h: In function 'kfence_alloc': >> ./include/linux/kfence.h:132:31: error: passing argument 1 of '__kfence_alloc' >> from incompatible p ointer type [-Wincompatible-pointer-types] >> 132 | return __kfence_alloc(s, size, flags); >> | ^ >> | | >> | struct kmem_cache * >> ./include/linux/kfence.h:103:41: note: expected 'struct kmem_cache *' >> but argument is of type 'str >> uct kmem_cache *' >> 103 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); >> | ~~~~~~~~~~~~~~~~~~~^ >> ------------------------------------------------------>8 >> >> So, this patch currently runs into compilation issues. linyu probably didn't have >> KFENCE enabled when compiling locally, which is why this error was missed. >> You can enable it as follows: >> >> Kernel hacking >> Memory Debugging >> [*] KFENCE: low-overhead sampling-based memory safety > > Hi Enze, > > Sorry only test on arm64. > > Could you help fix the compile issue and provide a correct change ? > > Or I need sometime to resolve the issue. > Thanks for pointing out this issue. I've taken a look at the compilation problem you mentioned. Based on my current understanding, the header dependencies are quite complex, and I couldn't find a straightforward fix without potentially affecting other parts of the codebase. Given the risk of introducing broader compilation errors, I think it might be safer to hold off on using the KFENCE_POOL_SIZE macro for now, unless there's a clear and safe path forward that I might have missed. I'm happy to discuss this further if you have any insights or suggestions. Thanks, Enze
Powered by blists - more mailing lists