From 1039bffd6ae9c75b42b7d148d6c1106134107b66 Mon Sep 17 00:00:00 2001 From: Xie Yuanbin Date: Tue, 28 Jul 2026 03:16:42 +0100 Subject: ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set, a user fault may trigger show_pte() without any lock. If another thread in the same process concurrently calls munmap(), the page table pages may be freed while show_pte() is still traversing them, causing a use-after-free in show_pte(). If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table of PMD are freed when show_pte() is running. Acquire mmap_write_lock() around show_pte() for user faults to fix the contention. For user faults, additionally restrict that show_pte() is called only when the addr is a user-space address (addr < TASK_SIZE). This is because the lock of tsk->mm only protects the virtual memory of user address space, furthermore, dumping the page tables of a kernel-space address for user faults is unnecessary and may have security implications. Keep everything unchanged for kernel faults, because the kernel is already in the "oops" state, acquiring a lock may risk a deadlock. Co-developed-by: Qi Xi Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults") Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com Acked-by: Lorenzo Stoakes (ARM) Reviewed-by: Linus Walleij Signed-off-by: Qi Xi Signed-off-by: Xie Yuanbin Signed-off-by: Russell King --- include/crypto/internal/simd.h | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 include/crypto/internal/simd.h (limited to 'include/crypto/internal/simd.h') diff --git a/include/crypto/internal/simd.h b/include/crypto/internal/simd.h new file mode 100644 index 000000000..f5e5d7b63 --- /dev/null +++ b/include/crypto/internal/simd.h @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Shared crypto simd helpers + */ + +#ifndef _CRYPTO_INTERNAL_SIMD_H +#define _CRYPTO_INTERNAL_SIMD_H + +#include +#include +#include + +struct simd_aead_alg; +struct aead_alg; + +int simd_register_aeads_compat(struct aead_alg *algs, int count, + struct simd_aead_alg **simd_algs); + +void simd_unregister_aeads(struct aead_alg *algs, int count, + struct simd_aead_alg **simd_algs); + +/* + * crypto_simd_usable() - is it allowed at this time to use SIMD instructions or + * access the SIMD register file? + * + * This delegates to may_use_simd(), except that this also returns false if SIMD + * in crypto code has been temporarily disabled on this CPU by the crypto + * self-tests, in order to test the no-SIMD fallback code. This override is + * currently limited to configurations where the "full" self-tests are enabled, + * because it might be a bit too invasive to be part of the "fast" self-tests. + */ +#ifdef CONFIG_CRYPTO_SELFTESTS_FULL +DECLARE_PER_CPU(bool, crypto_simd_disabled_for_test); +#define crypto_simd_usable() \ + (may_use_simd() && !this_cpu_read(crypto_simd_disabled_for_test)) +#else +#define crypto_simd_usable() may_use_simd() +#endif + +#endif /* _CRYPTO_INTERNAL_SIMD_H */ -- cgit v1.3.1