From: Samuel Holland <samuel.holland@sifive.com> To: Palmer Dabbelt <palmer@dabbelt.com>, linux-riscv@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Samuel Holland <samuel.holland@sifive.com>, stable@vger.kernel.org Subject: [PATCH] riscv: Fix spurious errors from __get/put_kernel_nofault Date: Mon, 11 Mar 2024 19:19:13 -0700 [thread overview] Message-ID: <20240312022030.320789-1-samuel.holland@sifive.com> (raw) These macros did not initialize __kr_err, so they could fail even if the access did not fault. Cc: stable@vger.kernel.org Fixes: d464118cdc41 ("riscv: implement __get_kernel_nofault and __put_user_nofault") Signed-off-by: Samuel Holland <samuel.holland@sifive.com> --- Found while testing the unaligned access speed series[1]. The observed behavior was that with RISCV_EFFICIENT_UNALIGNED_ACCESS=y, the copy_from_kernel_nofault() in prepend_copy() failed every time when filling out /proc/self/mounts, so all of the mount points were "xxx". I'm surprised this hasn't been seen before. For reference, I'm compiling with clang 18. [1]: https://lore.kernel.org/linux-riscv/20240308-disable_misaligned_probe_config-v9-0-a388770ba0ce@rivosinc.com/ arch/riscv/include/asm/uaccess.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h index ec0cab9fbddd..72ec1d9bd3f3 100644 --- a/arch/riscv/include/asm/uaccess.h +++ b/arch/riscv/include/asm/uaccess.h @@ -319,7 +319,7 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n) #define __get_kernel_nofault(dst, src, type, err_label) \ do { \ - long __kr_err; \ + long __kr_err = 0; \ \ __get_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err); \ if (unlikely(__kr_err)) \ @@ -328,7 +328,7 @@ do { \ #define __put_kernel_nofault(dst, src, type, err_label) \ do { \ - long __kr_err; \ + long __kr_err = 0; \ \ __put_user_nocheck(*((type *)(src)), (type *)(dst), __kr_err); \ if (unlikely(__kr_err)) \ -- 2.43.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
WARNING: multiple messages have this Message-ID (diff)
From: Samuel Holland <samuel.holland@sifive.com> To: Palmer Dabbelt <palmer@dabbelt.com>, linux-riscv@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Samuel Holland <samuel.holland@sifive.com>, stable@vger.kernel.org Subject: [PATCH] riscv: Fix spurious errors from __get/put_kernel_nofault Date: Mon, 11 Mar 2024 19:19:13 -0700 [thread overview] Message-ID: <20240312022030.320789-1-samuel.holland@sifive.com> (raw) These macros did not initialize __kr_err, so they could fail even if the access did not fault. Cc: stable@vger.kernel.org Fixes: d464118cdc41 ("riscv: implement __get_kernel_nofault and __put_user_nofault") Signed-off-by: Samuel Holland <samuel.holland@sifive.com> --- Found while testing the unaligned access speed series[1]. The observed behavior was that with RISCV_EFFICIENT_UNALIGNED_ACCESS=y, the copy_from_kernel_nofault() in prepend_copy() failed every time when filling out /proc/self/mounts, so all of the mount points were "xxx". I'm surprised this hasn't been seen before. For reference, I'm compiling with clang 18. [1]: https://lore.kernel.org/linux-riscv/20240308-disable_misaligned_probe_config-v9-0-a388770ba0ce@rivosinc.com/ arch/riscv/include/asm/uaccess.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h index ec0cab9fbddd..72ec1d9bd3f3 100644 --- a/arch/riscv/include/asm/uaccess.h +++ b/arch/riscv/include/asm/uaccess.h @@ -319,7 +319,7 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n) #define __get_kernel_nofault(dst, src, type, err_label) \ do { \ - long __kr_err; \ + long __kr_err = 0; \ \ __get_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err); \ if (unlikely(__kr_err)) \ @@ -328,7 +328,7 @@ do { \ #define __put_kernel_nofault(dst, src, type, err_label) \ do { \ - long __kr_err; \ + long __kr_err = 0; \ \ __put_user_nocheck(*((type *)(src)), (type *)(dst), __kr_err); \ if (unlikely(__kr_err)) \ -- 2.43.1
next reply other threads:[~2024-03-12 2:20 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-03-12 2:19 Samuel Holland [this message] 2024-03-12 2:19 ` [PATCH] riscv: Fix spurious errors from __get/put_kernel_nofault Samuel Holland 2024-03-13 2:53 ` Charlie Jenkins 2024-03-13 2:53 ` Charlie Jenkins 2024-03-13 3:05 ` Samuel Holland 2024-03-13 3:05 ` Samuel Holland 2024-03-13 3:22 ` Charlie Jenkins 2024-03-13 3:22 ` Charlie Jenkins 2024-03-25 7:42 ` Alexandre Ghiti 2024-03-25 7:42 ` Alexandre Ghiti 2024-03-26 21:10 ` patchwork-bot+linux-riscv 2024-03-26 21:10 ` patchwork-bot+linux-riscv
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