Commit 09a6adf5 authored by Victor Kamensky's avatar Victor Kamensky Committed by Will Deacon
Browse files

arm64: mm: unaligned access by user-land should be received as SIGBUS 



After 52d7523d (arm64: mm: allow the kernel to handle alignment faults on
user accesses) commit user-land accesses that produce unaligned exceptions
like in case of aarch32 ldm/stm/ldrd/strd instructions operating on
unaligned memory received by user-land as SIGSEGV. It is wrong, it should
be reported as SIGBUS as it was before 52d7523d commit.

Changed do_bad_area function to take signal and code parameters out of esr
value using fault_info table, so in case of do_alignment_fault fault
user-land will receive SIGBUS. Wrapped access to fault_info table into
esr_to_fault_info function.

Cc: <stable@vger.kernel.org>
Fixes: 52d7523d (arm64: mm: allow the kernel to handle alignment faults on user accesses)
Signed-off-by: default avatarVictor Kamensky <kamensky@cisco.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent a71c9a1c

arch/arm64/mm/fault.c

+24 −18
Original line number Diff line number Diff line
@@ -42,7 +42,20 @@ 
#include <asm/pgtable.h>

#include <asm/tlbflush.h>



static const char *fault_name(unsigned int esr);

struct fault_info {

	int	(*fn)(unsigned long addr, unsigned int esr,

		      struct pt_regs *regs);

	int	sig;

	int	code;

	const char *name;

};



static const struct fault_info fault_info[];



static inline const struct fault_info *esr_to_fault_info(unsigned int esr)

{

	return fault_info + (esr & 63);

}



#ifdef CONFIG_KPROBES

static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
@@ -197,10 +210,12 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, 
			    struct pt_regs *regs)

{

	struct siginfo si;

	const struct fault_info *inf;



	if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {

		inf = esr_to_fault_info(esr);

		pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",

			tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,

			tsk->comm, task_pid_nr(tsk), inf->name, sig,

			addr, esr);

		show_pte(tsk->mm, addr);

		show_regs(regs);
@@ -219,14 +234,16 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re 
{

	struct task_struct *tsk = current;

	struct mm_struct *mm = tsk->active_mm;

	const struct fault_info *inf;



	/*

	 * If we are in kernel mode at this point, we have no context to

	 * handle this fault with.

	 */

	if (user_mode(regs))

		__do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);

	else

	if (user_mode(regs)) {

		inf = esr_to_fault_info(esr);

		__do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs);

	} else

		__do_kernel_fault(mm, addr, esr, regs);

}
@@ -488,12 +505,7 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs) 
	return 1;

}



static const struct fault_info {

	int	(*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);

	int	sig;

	int	code;

	const char *name;

} fault_info[] = {

static const struct fault_info fault_info[] = {

	{ do_bad,		SIGBUS,  0,		"ttbr address size fault"	},

	{ do_bad,		SIGBUS,  0,		"level 1 address size fault"	},

	{ do_bad,		SIGBUS,  0,		"level 2 address size fault"	},
@@ -560,19 +572,13 @@ static const struct fault_info { 
	{ do_bad,		SIGBUS,  0,		"unknown 63"			},

};



static const char *fault_name(unsigned int esr)

{

	const struct fault_info *inf = fault_info + (esr & 63);

	return inf->name;

}



/*

 * Dispatch a data abort to the relevant handler.

 */

asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,

					 struct pt_regs *regs)

{

	const struct fault_info *inf = fault_info + (esr & 63);

	const struct fault_info *inf = esr_to_fault_info(esr);

	struct siginfo info;



	if (!inf->fn(addr, esr, regs))

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