From: Jing Xiangfeng <jingxiangfeng@huawei.com> To: <linux@armlinux.org.uk>, <ebiederm@xmission.com>, <kstewart@linuxfoundation.org>, <gregkh@linuxfoundation.org>, <gustavo@embeddedor.com>, <bhelgaas@google.com>, <jingxiangfeng@huawei.com>, <tglx@linutronix.de>, <sakari.ailus@linux.intel.com> Cc: <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org> Subject: [PATCH] arm: fix page faults in do_alignment Date: Fri, 30 Aug 2019 21:31:17 +0800 [thread overview] Message-ID: <1567171877-101949-1-git-send-email-jingxiangfeng@huawei.com> (raw) The function do_alignment can handle misaligned address for user and kernel space. If it is a userspace access, do_alignment may fail on a low-memory situation, because page faults are disabled in probe_kernel_address. Fix this by using __copy_from_user stead of probe_kernel_address. Fixes: b255188 ("ARM: fix scheduling while atomic warning in alignment handling code") Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com> --- arch/arm/mm/alignment.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c index 04b3643..2ccabd3 100644 --- a/arch/arm/mm/alignment.c +++ b/arch/arm/mm/alignment.c @@ -774,6 +774,7 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer unsigned long instr = 0, instrptr; int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); unsigned int type; + mm_segment_t fs; unsigned int fault; u16 tinstr = 0; int isize = 4; @@ -784,16 +785,22 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer instrptr = instruction_pointer(regs); + fs = get_fs(); + set_fs(KERNEL_DS); if (thumb_mode(regs)) { u16 *ptr = (u16 *)(instrptr & ~1); - fault = probe_kernel_address(ptr, tinstr); + fault = __copy_from_user(tinstr, + (__force const void __user *)ptr, + sizeof(tinstr)); tinstr = __mem_to_opcode_thumb16(tinstr); if (!fault) { if (cpu_architecture() >= CPU_ARCH_ARMv7 && IS_T32(tinstr)) { /* Thumb-2 32-bit */ u16 tinst2 = 0; - fault = probe_kernel_address(ptr + 1, tinst2); + fault = __copy_from_user(tinst2, + (__force const void __user *)(ptr+1), + sizeof(tinst2)); tinst2 = __mem_to_opcode_thumb16(tinst2); instr = __opcode_thumb32_compose(tinstr, tinst2); thumb2_32b = 1; @@ -803,10 +810,13 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer } } } else { - fault = probe_kernel_address((void *)instrptr, instr); + fault = __copy_from_user(instr, + (__force const void __user *)instrptr, + sizeof(instr)); instr = __mem_to_opcode_arm(instr); } + set_fs(fs); if (fault) { type = TYPE_FAULT; goto bad_or_fault; -- 1.8.3.1
WARNING: multiple messages have this Message-ID (diff)
From: Jing Xiangfeng <jingxiangfeng@huawei.com> To: <linux@armlinux.org.uk>, <ebiederm@xmission.com>, <kstewart@linuxfoundation.org>, <gregkh@linuxfoundation.org>, <gustavo@embeddedor.com>, <bhelgaas@google.com>, <jingxiangfeng@huawei.com>, <tglx@linutronix.de>, <sakari.ailus@linux.intel.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm: fix page faults in do_alignment Date: Fri, 30 Aug 2019 21:31:17 +0800 [thread overview] Message-ID: <1567171877-101949-1-git-send-email-jingxiangfeng@huawei.com> (raw) The function do_alignment can handle misaligned address for user and kernel space. If it is a userspace access, do_alignment may fail on a low-memory situation, because page faults are disabled in probe_kernel_address. Fix this by using __copy_from_user stead of probe_kernel_address. Fixes: b255188 ("ARM: fix scheduling while atomic warning in alignment handling code") Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com> --- arch/arm/mm/alignment.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c index 04b3643..2ccabd3 100644 --- a/arch/arm/mm/alignment.c +++ b/arch/arm/mm/alignment.c @@ -774,6 +774,7 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer unsigned long instr = 0, instrptr; int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); unsigned int type; + mm_segment_t fs; unsigned int fault; u16 tinstr = 0; int isize = 4; @@ -784,16 +785,22 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer instrptr = instruction_pointer(regs); + fs = get_fs(); + set_fs(KERNEL_DS); if (thumb_mode(regs)) { u16 *ptr = (u16 *)(instrptr & ~1); - fault = probe_kernel_address(ptr, tinstr); + fault = __copy_from_user(tinstr, + (__force const void __user *)ptr, + sizeof(tinstr)); tinstr = __mem_to_opcode_thumb16(tinstr); if (!fault) { if (cpu_architecture() >= CPU_ARCH_ARMv7 && IS_T32(tinstr)) { /* Thumb-2 32-bit */ u16 tinst2 = 0; - fault = probe_kernel_address(ptr + 1, tinst2); + fault = __copy_from_user(tinst2, + (__force const void __user *)(ptr+1), + sizeof(tinst2)); tinst2 = __mem_to_opcode_thumb16(tinst2); instr = __opcode_thumb32_compose(tinstr, tinst2); thumb2_32b = 1; @@ -803,10 +810,13 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer } } } else { - fault = probe_kernel_address((void *)instrptr, instr); + fault = __copy_from_user(instr, + (__force const void __user *)instrptr, + sizeof(instr)); instr = __mem_to_opcode_arm(instr); } + set_fs(fs); if (fault) { type = TYPE_FAULT; goto bad_or_fault; -- 1.8.3.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2019-08-30 13:25 UTC|newest] Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-30 13:31 Jing Xiangfeng [this message] 2019-08-30 13:31 ` [PATCH] arm: fix page faults in do_alignment Jing Xiangfeng 2019-08-30 13:35 ` Russell King - ARM Linux admin 2019-08-30 13:35 ` Russell King - ARM Linux admin 2019-08-30 13:48 ` Russell King - ARM Linux admin 2019-08-30 13:48 ` Russell King - ARM Linux admin 2019-08-30 19:45 ` Eric W. Biederman 2019-08-30 19:45 ` Eric W. Biederman 2019-08-30 19:45 ` Eric W. Biederman 2019-08-30 20:30 ` Russell King - ARM Linux admin 2019-08-30 20:30 ` Russell King - ARM Linux admin 2019-08-30 21:02 ` Eric W. Biederman 2019-08-30 21:02 ` Eric W. Biederman 2019-08-30 21:02 ` Eric W. Biederman 2019-08-30 22:29 ` Russell King - ARM Linux admin 2019-08-30 22:29 ` Russell King - ARM Linux admin 2019-09-02 17:36 ` Eric W. Biederman 2019-09-02 17:36 ` Eric W. Biederman 2019-09-02 17:36 ` Eric W. Biederman 2019-09-04 2:17 ` Jing Xiangfeng 2019-09-04 2:17 ` Jing Xiangfeng 2019-09-06 15:17 ` Russell King - ARM Linux admin 2019-09-06 15:17 ` Russell King - ARM Linux admin 2019-09-15 18:34 ` Russell King - ARM Linux admin 2019-09-15 18:34 ` Russell King - ARM Linux admin 2019-09-16 14:31 ` Eric W. Biederman 2019-09-16 14:31 ` Eric W. Biederman 2019-09-16 14:31 ` Eric W. Biederman 2019-08-31 1:49 ` Jing Xiangfeng 2019-08-31 1:49 ` Jing Xiangfeng 2019-08-31 7:55 ` Russell King - ARM Linux admin 2019-08-31 7:55 ` Russell King - ARM Linux admin 2019-08-31 9:16 ` Jing Xiangfeng 2019-08-31 9:16 ` Jing Xiangfeng 2019-08-31 12:48 ` kbuild test robot
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