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powerpc/watchpoint/ptrace: Fix SETHWDEBUG when CONFIG_HAVE_HW_BREAKPOINT=N

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When kernel is compiled with CONFIG_HAVE_HW_BREAKPOINT=N, user can
still create watchpoint using PPC_PTRACE_SETHWDEBUG, with limited
functionalities. But, such watchpoints are never firing because of
the missing privilege settings. Fix that.

It's safe to set HW_BRK_TYPE_PRIV_ALL because we don't really leak
any kernel address in signal info. Setting HW_BRK_TYPE_PRIV_ALL will
also help to find scenarios when kernel accesses user memory.

Reported-by: Pedro Miraglia Franco de Carvalho <pedromfc@linux.ibm.com>
Suggested-by: Pedro Miraglia Franco de Carvalho <pedromfc@linux.ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200902042945.129369-4-ravi.bangoria@linux.ibm.com
This commit is contained in:
Ravi Bangoria 2020-09-02 09:59:40 +05:30 committed by Michael Ellerman
parent 4441eb0233
commit 9b6b7c680c
1 changed files with 1 additions and 1 deletions
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2
arch/powerpc/kernel/ptrace/ptrace-noadv.c
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@ -217,7 +217,7 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
return -EIO; return -EIO;
brk.address = ALIGN_DOWN(bp_info->addr, HW_BREAKPOINT_SIZE); brk.address = ALIGN_DOWN(bp_info->addr, HW_BREAKPOINT_SIZE);
brk.type = HW_BRK_TYPE_TRANSLATE; brk.type = HW_BRK_TYPE_TRANSLATE | HW_BRK_TYPE_PRIV_ALL;
brk.len = DABR_MAX_LEN; brk.len = DABR_MAX_LEN;
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ) if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
brk.type |= HW_BRK_TYPE_READ; brk.type |= HW_BRK_TYPE_READ;