Commit 5b835d4c authored by Max Filippov's avatar Max Filippov
Browse files

xtensa: use XCHAL_NUM_AREGS as pt_regs::areg size 



struct pt_regs is used to access both kernel and user exception frames.
User exception frames may contain up to XCHAL_NUM_AREG registers that
task creation and signal delivery code may access, but pt_regs::areg
array has only 16 entries that cover only the kernel exception frame.
This results in the following build error:

arch/xtensa/kernel/process.c: In function 'copy_thread':
arch/xtensa/kernel/process.c:262:52: error: array subscript 53 is above
           array bounds of 'long unsigned int[16]' [-Werror=array-bounds]
  262 |                                 put_user(regs->areg[caller_ars+1],

Change struct pt_regs::areg size to XCHAL_NUM_AREGS so that it covers
the whole user exception frame. Adjust task_pt_regs and drop additional
register copying code from copy_thread now that the whole user exception
stack frame is copied.

Reported-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
parent 6fad9ddc

arch/xtensa/include/asm/ptrace.h

+3 −4
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 
#ifndef __ASSEMBLY__



#include <asm/coprocessor.h>

#include <asm/core.h>



/*

 * This struct defines the way the registers are stored on the
@@ -77,14 +78,12 @@ struct pt_regs { 
	/* current register frame.

	 * Note: The ESF for kernel exceptions ends after 16 registers!

	 */

	unsigned long areg[16];

	unsigned long areg[XCHAL_NUM_AREGS];

};



#include <asm/core.h>



# define arch_has_single_step()	(1)

# define task_pt_regs(tsk) ((struct pt_regs*) \

	(task_stack_page(tsk) + KERNEL_STACK_SIZE - (XCHAL_NUM_AREGS-16)*4) - 1)

	(task_stack_page(tsk) + KERNEL_STACK_SIZE) - 1)

# define user_mode(regs) (((regs)->ps & 0x00000020)!=0)

# define instruction_pointer(regs) ((regs)->pc)

# define return_pointer(regs) (MAKE_PC_FROM_RA((regs)->areg[0], \

arch/xtensa/kernel/process.c

+0 −10
Original line number Diff line number Diff line
@@ -232,10 +232,6 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn, 
		p->thread.ra = MAKE_RA_FOR_CALL(

				(unsigned long)ret_from_fork, 0x1);



		/* This does not copy all the regs.

		 * In a bout of brilliance or madness,

		 * ARs beyond a0-a15 exist past the end of the struct.

		 */

		*childregs = *regs;

		childregs->areg[1] = usp;

		childregs->areg[2] = 0;
@@ -265,14 +261,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn, 
			childregs->wmask = 1;

			childregs->windowstart = 1;

			childregs->windowbase = 0;

		} else {

			int len = childregs->wmask & ~0xf;

			memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],

			       &regs->areg[XCHAL_NUM_AREGS - len/4], len);

		}



		childregs->syscall = regs->syscall;



		if (clone_flags & CLONE_SETTLS)

			childregs->threadptr = tls;

	} else {