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signal/ptrace: Add force_sig_ptrace_errno_trap and use it where needed

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There are so many places that build struct siginfo by hand that at
least one of them is bound to get it wrong.  A handful of cases in the
kernel arguably did just that when using the errno field of siginfo to
pass no errno values to userspace.  The usage is limited to a single
si_code so at least does not mess up anything else.

Encapsulate this questionable pattern in a helper function so
that the userspace ABI is preserved.

Update all of the places that use this pattern to use the new helper
function.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2018-01-22 14:37:25 -06:00
parent 47355040d2
commit f71dd7dc2d
6 changed files with 25 additions and 23 deletions
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8
arch/arm/kernel/ptrace.c
View File

@ -390,7 +390,6 @@ static void ptrace_hbptriggered(struct perf_event *bp,
struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
long num;
int i;
siginfo_t info;
for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i)
if (current->thread.debug.hbp[i] == bp)
@ -398,12 +397,7 @@ static void ptrace_hbptriggered(struct perf_event *bp,
num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i);
info.si_signo = SIGTRAP;
info.si_errno = (int)num;
info.si_code = TRAP_HWBKPT;
info.si_addr = (void __user *)(bkpt->trigger);
force_sig_info(SIGTRAP, &info, current);
force_sig_ptrace_errno_trap((int)num, (void __user *)(bkpt->trigger));
}
/*

6
arch/arm64/kernel/ptrace.c
View File

@ -190,21 +190,23 @@ static void ptrace_hbptriggered(struct perf_event *bp,
#ifdef CONFIG_COMPAT
if (is_compat_task()) {
int si_errno = 0;
int i;
for (i = 0; i < ARM_MAX_BRP; ++i) {
if (current->thread.debug.hbp_break[i] == bp) {
info.si_errno = (i << 1) + 1;
si_errno = (i << 1) + 1;
break;
}
}
for (i = 0; i < ARM_MAX_WRP; ++i) {
if (current->thread.debug.hbp_watch[i] == bp) {
info.si_errno = -((i << 1) + 1);
si_errno = -((i << 1) + 1);
break;
}
}
force_sig_ptrace_errno_trap(si_errno, (void __user *)bkpt->trigger);
}
#endif
force_sig_info(SIGTRAP, &info, current);

9
arch/powerpc/kernel/process.c
View File

@ -603,19 +603,14 @@ EXPORT_SYMBOL(flush_all_to_thread);
void do_send_trap(struct pt_regs *regs, unsigned long address,
unsigned long error_code, int breakpt)
{
siginfo_t info;
current->thread.trap_nr = TRAP_HWBKPT;
if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
11, SIGSEGV) == NOTIFY_STOP)
return;
/* Deliver the signal to userspace */
info.si_signo = SIGTRAP;
info.si_errno = breakpt; /* breakpoint or watchpoint id */
info.si_code = TRAP_HWBKPT;
info.si_addr = (void __user *)address;
force_sig_info(SIGTRAP, &info, current);
force_sig_ptrace_errno_trap(breakpt, /* breakpoint or watchpoint id */
(void __user *)address);
}
#else /* !CONFIG_PPC_ADV_DEBUG_REGS */
void do_break (struct pt_regs *regs, unsigned long address,

8
arch/xtensa/kernel/ptrace.c
View File

@ -278,7 +278,6 @@ static void ptrace_hbptriggered(struct perf_event *bp,
struct pt_regs *regs)
{
int i;
siginfo_t info;
struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
if (bp->attr.bp_type & HW_BREAKPOINT_X) {
@ -293,12 +292,7 @@ static void ptrace_hbptriggered(struct perf_event *bp,
i = (i << 1) | 1;
}
info.si_signo = SIGTRAP;
info.si_errno = i;
info.si_code = TRAP_HWBKPT;
info.si_addr = (void __user *)bkpt->address;
force_sig_info(SIGTRAP, &info, current);
force_sig_ptrace_errno_trap(i, (void __user *)bkpt->address);
}
static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)

2
include/linux/sched/signal.h
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@ -311,6 +311,8 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
int force_sig_pkuerr(void __user *addr, u32 pkey);
int force_sig_ptrace_errno_trap(int errno, void __user *addr);
extern int send_sig_info(int, struct siginfo *, struct task_struct *);
extern int force_sigsegv(int, struct task_struct *);
extern int force_sig_info(int, struct siginfo *, struct task_struct *);

15
kernel/signal.c
View File

@ -1599,6 +1599,21 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
}
#endif
/* For the crazy architectures that include trap information in
* the errno field, instead of an actual errno value.
*/
int force_sig_ptrace_errno_trap(int errno, void __user *addr)
{
struct siginfo info;
clear_siginfo(&info);
info.si_signo = SIGTRAP;
info.si_errno = errno;
info.si_code = TRAP_HWBKPT;
info.si_addr = addr;
return force_sig_info(info.si_signo, &info, current);
}
int kill_pgrp(struct pid *pid, int sig, int priv)
{
int ret;