diff mbox series

[v6,3/8] powerpc/watchpoint/ptrace: Fix SETHWDEBUG when CONFIG_HAVE_HW_BREAKPOINT=N

Message ID 20200902042945.129369-4-ravi.bangoria@linux.ibm.com (mailing list archive)
State Accepted
Commit 9b6b7c680cc20971444d9f836e49fc98848bcd0a
Headers show
Series powerpc/watchpoint: Bug fixes plus new feature flag | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (35f066fda170dde0a31f1447547a5d30b83c3920)
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
snowpatch_ozlabs/needsstable success Patch has no Fixes tags

Commit Message

Ravi Bangoria Sept. 2, 2020, 4:29 a.m. UTC 
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>
---
 arch/powerpc/kernel/ptrace/ptrace-noadv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Rogerio Alves Sept. 17, 2020, 1:25 p.m. UTC | #1 
On 9/2/20 1:29 AM, Ravi Bangoria wrote:
> 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>
Tested-by: Rogerio Alves <rcardoso@linux.ibm.com>
> ---
>   arch/powerpc/kernel/ptrace/ptrace-noadv.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
> index 697c7e4b5877..57a0ab822334 100644
> --- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
> +++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
> @@ -217,7 +217,7 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
>   		return -EIO;
>   
>   	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;
>   	if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
>   		brk.type |= HW_BRK_TYPE_READ;
>
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
index 697c7e4b5877..57a0ab822334 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
@@ -217,7 +217,7 @@  long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
 		return -EIO;
 
 	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;
 	if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
 		brk.type |= HW_BRK_TYPE_READ;