From 96f1b00138cb8f04c742c82d0a7c460b2202e887 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Tue, 8 Jun 2021 19:39:25 -0700 Subject: ARCv2: save ABI registers across signal handling ARCv2 has some configuration dependent registers (r30, r58, r59) which could be targetted by the compiler. To keep the ABI stable, these were unconditionally part of the glibc ABI (sysdeps/unix/sysv/linux/arc/sys/ucontext.h:mcontext_t) however we missed populating them (by saving/restoring them across signal handling). This patch fixes the issue by - adding arcv2 ABI regs to kernel struct sigcontext - populating them during signal handling Change to struct sigcontext might seem like a glibc ABI change (although it primarily uses ucontext_t:mcontext_t) but the fact is - it has only been extended (existing fields are not touched) - the old sigcontext was ABI incomplete to begin with anyways Fixes: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/53 Cc: Tested-by: kernel test robot Reported-by: Vladimir Isaev Signed-off-by: Vineet Gupta --- arch/arc/include/uapi/asm/sigcontext.h | 1 + arch/arc/kernel/signal.c | 43 ++++++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+) diff --git a/arch/arc/include/uapi/asm/sigcontext.h b/arch/arc/include/uapi/asm/sigcontext.h index 95f8a4380e11..7a5449dfcb29 100644 --- a/arch/arc/include/uapi/asm/sigcontext.h +++ b/arch/arc/include/uapi/asm/sigcontext.h @@ -18,6 +18,7 @@ */ struct sigcontext { struct user_regs_struct regs; + struct user_regs_arcv2 v2abi; }; #endif /* _ASM_ARC_SIGCONTEXT_H */ diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c index b3ccb9e5ffe4..cb2f88502baf 100644 --- a/arch/arc/kernel/signal.c +++ b/arch/arc/kernel/signal.c @@ -61,6 +61,41 @@ struct rt_sigframe { unsigned int sigret_magic; }; +static int save_arcv2_regs(struct sigcontext *mctx, struct pt_regs *regs) +{ + int err = 0; +#ifndef CONFIG_ISA_ARCOMPACT + struct user_regs_arcv2 v2abi; + + v2abi.r30 = regs->r30; +#ifdef CONFIG_ARC_HAS_ACCL_REGS + v2abi.r58 = regs->r58; + v2abi.r59 = regs->r59; +#else + v2abi.r58 = v2abi.r59 = 0; +#endif + err = __copy_to_user(&mctx->v2abi, &v2abi, sizeof(v2abi)); +#endif + return err; +} + +static int restore_arcv2_regs(struct sigcontext *mctx, struct pt_regs *regs) +{ + int err = 0; +#ifndef CONFIG_ISA_ARCOMPACT + struct user_regs_arcv2 v2abi; + + err = __copy_from_user(&v2abi, &mctx->v2abi, sizeof(v2abi)); + + regs->r30 = v2abi.r30; +#ifdef CONFIG_ARC_HAS_ACCL_REGS + regs->r58 = v2abi.r58; + regs->r59 = v2abi.r59; +#endif +#endif + return err; +} + static int stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs, sigset_t *set) @@ -94,6 +129,10 @@ stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs, err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch, sizeof(sf->uc.uc_mcontext.regs.scratch)); + + if (is_isa_arcv2()) + err |= save_arcv2_regs(&(sf->uc.uc_mcontext), regs); + err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t)); return err ? -EFAULT : 0; @@ -109,6 +148,10 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf) err |= __copy_from_user(&uregs.scratch, &(sf->uc.uc_mcontext.regs.scratch), sizeof(sf->uc.uc_mcontext.regs.scratch)); + + if (is_isa_arcv2()) + err |= restore_arcv2_regs(&(sf->uc.uc_mcontext), regs); + if (err) return -EFAULT; -- cgit v1.2.3 From 110febc0148f8ab867344061d5cf95ee1e1ebb3e Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Fri, 26 Feb 2021 10:35:39 -0800 Subject: ARC: fix CONFIG_HARDENED_USERCOPY Currently enabling this triggers a warning | usercopy: Kernel memory overwrite attempt detected to kernel text (offset 155633, size 11)! | usercopy: BUG: failure at mm/usercopy.c:99/usercopy_abort()! | |gcc generated __builtin_trap |Path: /bin/busybox |CPU: 0 PID: 84 Comm: init Not tainted 5.4.22 | |[ECR ]: 0x00090005 => gcc generated __builtin_trap |[EFA ]: 0x9024fcaa |[BLINK ]: usercopy_abort+0x8a/0x8c |[ERET ]: memfd_fcntl+0x0/0x470 |[STAT32]: 0x80080802 : IE K |... |... |Stack Trace: | memfd_fcntl+0x0/0x470 | usercopy_abort+0x8a/0x8c | __check_object_size+0x10e/0x138 | copy_strings+0x1f4/0x38c | __do_execve_file+0x352/0x848 | EV_Trap+0xcc/0xd0 The issue is triggered by an allocation in "init reclaimed" region. ARC _stext emcompasses the init region (for historical reasons we wanted the init.text to be under .text as well). This however trips up __check_object_size()->check_kernel_text_object() which treats this as object bleeding into kernel text. Fix that by rezoning _stext to start from regular kernel .text and leave out .init altogether. Fixes: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/15 Reported-by: Evgeniy Didin Reviewed-by: Kees Cook Signed-off-by: Vineet Gupta --- arch/arc/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S index 33ce59d91461..e2146a8da195 100644 --- a/arch/arc/kernel/vmlinux.lds.S +++ b/arch/arc/kernel/vmlinux.lds.S @@ -57,7 +57,6 @@ SECTIONS .init.ramfs : { INIT_RAM_FS } . = ALIGN(PAGE_SIZE); - _stext = .; HEAD_TEXT_SECTION INIT_TEXT_SECTION(L1_CACHE_BYTES) @@ -83,6 +82,7 @@ SECTIONS .text : { _text = .; + _stext = .; TEXT_TEXT SCHED_TEXT CPUIDLE_TEXT -- cgit v1.2.3