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h8300/ptrace: Fix incorrect register transfer count

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regs_set() and regs_get() are vulnerable to an off-by-1 buffer overrun
if CONFIG_CPU_H8S is set, since this adds an extra entry to
register_offset[] but not to user_regs_struct.

So, iterate over user_regs_struct based on its actual size, not based on
the length of register_offset[].

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dave Martin 2017-03-27 15:10:54 +01:00 committed by Linus Torvalds
parent fb411b837b
commit 502585c755
1 changed files with 5 additions and 3 deletions
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8
arch/h8300/kernel/ptrace.c
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@ -95,7 +95,8 @@ static int regs_get(struct task_struct *target,
long *reg = (long *)&regs;
/* build user regs in buffer */
for (r = 0; r < ARRAY_SIZE(register_offset); r++)
BUILD_BUG_ON(sizeof(regs) % sizeof(long) != 0);
for (r = 0; r < sizeof(regs) / sizeof(long); r++)
*reg++ = h8300_get_reg(target, r);
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
@ -113,7 +114,8 @@ static int regs_set(struct task_struct *target,
long *reg;
/* build user regs in buffer */
for (reg = (long *)&regs, r = 0; r < ARRAY_SIZE(register_offset); r++)
BUILD_BUG_ON(sizeof(regs) % sizeof(long) != 0);
for (reg = (long *)&regs, r = 0; r < sizeof(regs) / sizeof(long); r++)
*reg++ = h8300_get_reg(target, r);
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
@ -122,7 +124,7 @@ static int regs_set(struct task_struct *target,
return ret;
/* write back to pt_regs */
for (reg = (long *)&regs, r = 0; r < ARRAY_SIZE(register_offset); r++)
for (reg = (long *)&regs, r = 0; r < sizeof(regs) / sizeof(long); r++)
h8300_put_reg(target, r, *reg++);
return 0;
}