[PATCH 2/3] arm64: signal: sigreturn() and rt_sigreturn() sometime returns the wrong signals
From: Liam Howlett <hidden>
Date: 2021-04-20 16:50:49
Also in:
bpf, lkml, netdev
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
arm64_notify_segfault() was used to force a SIGSEGV in all error cases in sigreturn() and rt_sigreturn() to avoid writing a new sig handler. There is now a better sig handler to use which does not search the VMA address space and return a slightly incorrect error code. Restore the older and correct si_code of SI_KERNEL by using arm64_notify_die(). In the case of !access_ok(), simply return SIGSEGV with si_code SEGV_ACCERR. This change requires exporting arm64_notfiy_die() to the arm64 traps.h Fixes: f71016a8a8c5 (arm64: signal: Call arm64_notify_segfault when failing to deliver signal) Signed-off-by: Liam R. Howlett <redacted> --- arch/arm64/include/asm/traps.h | 2 ++ arch/arm64/kernel/signal.c | 8 ++++++-- arch/arm64/kernel/signal32.c | 18 ++++++++++++++---- 3 files changed, 22 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 54f32a0675df..9b76144fcba6 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h@@ -29,6 +29,8 @@ void arm64_notify_segfault(unsigned long addr); void arm64_force_sig_fault(int signo, int code, unsigned long far, const char *str); void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, const char *str); void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far, const char *str); +void arm64_notify_die(const char *str, struct pt_regs *regs, int signo, + int sicode, unsigned long far, int err); /* * Move regs->pc to next instruction and do necessary setup before it
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 6237486ff6bb..9fde6dc760c3 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c@@ -544,7 +544,7 @@ SYSCALL_DEFINE0(rt_sigreturn) frame = (struct rt_sigframe __user *)regs->sp; if (!access_ok(frame, sizeof (*frame))) - goto badframe; + goto e_access; if (restore_sigframe(regs, frame)) goto badframe;
@@ -555,7 +555,11 @@ SYSCALL_DEFINE0(rt_sigreturn) return regs->regs[0]; badframe: - arm64_notify_segfault(regs->sp); + arm64_notify_die("Bad frame", regs, SIGSEGV, SI_KERNEL, regs->sp, 0); + return 0; + +e_access: + force_signal_inject(SIGSEGV, SEGV_ACCERR, regs->sp, 0); return 0; }
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 2f507f565c48..af8b6c0eb8aa 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c@@ -248,7 +248,7 @@ COMPAT_SYSCALL_DEFINE0(sigreturn) frame = (struct compat_sigframe __user *)regs->compat_sp; if (!access_ok(frame, sizeof (*frame))) - goto badframe; + goto e_access; if (compat_restore_sigframe(regs, frame)) goto badframe;
@@ -256,7 +256,12 @@ COMPAT_SYSCALL_DEFINE0(sigreturn) return regs->regs[0]; badframe: - arm64_notify_segfault(regs->compat_sp); + arm64_notify_die("Bad frame", regs, SIGSEGV, SI_KERNEL, + regs->compat_sp, 0); + return 0; + +e_access: + force_signal_inject(SIGSEGV, SEGV_ACCERR, regs->compat_sp, 0); return 0; }
@@ -279,7 +284,7 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn) frame = (struct compat_rt_sigframe __user *)regs->compat_sp; if (!access_ok(frame, sizeof (*frame))) - goto badframe; + goto e_access; if (compat_restore_sigframe(regs, &frame->sig)) goto badframe;
@@ -290,7 +295,12 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn) return regs->regs[0]; badframe: - arm64_notify_segfault(regs->compat_sp); + arm64_notify_die("Bad frame", regs, SIGSEGV, SI_KERNEL, + regs->compat_sp, 0); + return 0; + +e_access: + force_signal_inject(SIGSEGV, SEGV_ACCERR, regs->compat_sp, 0); return 0; }
--
2.30.2
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