From ad9e202aa1ce571b1d7fed969d06f66067f8a086 Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Wed, 18 Jan 2017 16:25:24 +0000 Subject: [PATCH] arm64/ptrace: Reject attempts to set incomplete hardware breakpoint fields We cannot preserve partial fields for hardware breakpoints, because the values written by userspace to the hardware breakpoint registers can't subsequently be recovered intact from the hardware. So, just reject attempts to write incomplete fields with -EINVAL. Cc: # 3.7.x- Fixes: 478fcb2cdb23 ("arm64: Debugging support") Signed-off-by: Dave Martin Acked-by: Will Deacon Signed-off-by: Catalin Marinas --- arch/arm64/kernel/ptrace.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 91c4719dfc00..a22161ccf447 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -551,6 +551,8 @@ static int hw_break_set(struct task_struct *target, /* (address, ctrl) registers */ limit = regset->n * regset->size; while (count && offset < limit) { + if (count < PTRACE_HBP_ADDR_SZ) + return -EINVAL; ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &addr, offset, offset + PTRACE_HBP_ADDR_SZ); if (ret) @@ -560,6 +562,8 @@ static int hw_break_set(struct task_struct *target, return ret; offset += PTRACE_HBP_ADDR_SZ; + if (!count) + break; ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &ctrl, offset, offset + PTRACE_HBP_CTRL_SZ); if (ret)