Re: [PATCH v17 3/3] arm64: expose FAR_EL1 tag bits in siginfo
flat view
From: Eric W. Biederman <hidden>
Date: 2020-11-17 13:40:45
Also in:
linux-arm-kernel
Peter Collingbourne [off-list ref] writes:
quoted hunk
diff --git a/kernel/signal.c b/kernel/signal.c index 8f34819e80de..16be62e6d341 100644 --- a/kernel/signal.c +++ b/kernel/signal.c@@ -1650,6 +1650,15 @@ void force_sigsegv(int sig) force_sig(SIGSEGV); } +static void __user *get_si_addr(void __user *addr, unsigned long sig, + unsigned long si_code) +{ + if (current->sighand->action[sig - 1].sa.sa_flags & SA_EXPOSE_TAGBITS) + return addr;
Apologies for not seeing this before but this part of the patch is buggy. It is using current->sighand->action when the destination task may not be current. send_sig_fault and send_sig_mcerr may somewhat legitimately be used to send faults to other processes. Now that I think about it there are interactions with PTRACE_GETSIGINFO/PTRACE_SETSIGINFO. Can we move the masking into get_signal after the ptrace handling? That way everything in the core of the kernel deals with unmasked si_addr values and we only mask the address just before sending it to userspace? Eric
quoted hunk
+ return arch_untagged_si_addr(addr, sig, si_code); +} + int force_sig_fault_to_task(int sig, int code, void __user *addr ___ARCH_SI_TRAPNO(int trapno) ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)@@ -1661,7 +1670,7 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr info.si_signo = sig; info.si_errno = 0; info.si_code = code; - info.si_addr = addr; + info.si_addr = get_si_addr(addr, sig, code); #ifdef __ARCH_SI_TRAPNO info.si_trapno = trapno; #endif@@ -1693,7 +1702,7 @@ int send_sig_fault(int sig, int code, void __user *addr info.si_signo = sig; info.si_errno = 0; info.si_code = code; - info.si_addr = addr; + info.si_addr = get_si_addr(addr, sig, code); #ifdef __ARCH_SI_TRAPNO info.si_trapno = trapno; #endif@@ -1714,7 +1723,7 @@ int force_sig_mceerr(int code, void __user *addr, short lsb) info.si_signo = SIGBUS; info.si_errno = 0; info.si_code = code; - info.si_addr = addr; + info.si_addr = get_si_addr(addr, SIGBUS, code); info.si_addr_lsb = lsb; return force_sig_info(&info); }@@ -1728,7 +1737,7 @@ int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct * info.si_signo = SIGBUS; info.si_errno = 0; info.si_code = code; - info.si_addr = addr; + info.si_addr = get_si_addr(addr, SIGBUS, code); info.si_addr_lsb = lsb; return send_sig_info(info.si_signo, &info, t); }@@ -1742,7 +1751,7 @@ int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper) info.si_signo = SIGSEGV; info.si_errno = 0; info.si_code = SEGV_BNDERR; - info.si_addr = addr; + info.si_addr = get_si_addr(addr, SIGSEGV, SEGV_BNDERR); info.si_lower = lower; info.si_upper = upper; return force_sig_info(&info);@@ -1757,7 +1766,7 @@ int force_sig_pkuerr(void __user *addr, u32 pkey) info.si_signo = SIGSEGV; info.si_errno = 0; info.si_code = SEGV_PKUERR; - info.si_addr = addr; + info.si_addr = get_si_addr(addr, SIGSEGV, SEGV_PKUERR); info.si_pkey = pkey; return force_sig_info(&info); }@@ -1774,7 +1783,7 @@ int force_sig_ptrace_errno_trap(int errno, void __user *addr) info.si_signo = SIGTRAP; info.si_errno = errno; info.si_code = TRAP_HWBKPT; - info.si_addr = addr; + info.si_addr = get_si_addr(addr, SIGTRAP, TRAP_HWBKPT); return force_sig_info(&info); }