[v2,05/12] powerpc/pseries/ras: FWNMI_VALID off by one
diff mbox series

Message ID 20200325103410.157573-6-npiggin@gmail.com
State New
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Series
  • powerpc/64: machine check and system reset fixes
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Context Check Description
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Commit Message

Nicholas Piggin March 25, 2020, 10:34 a.m. UTC
This was discovered developing qemu fwnmi sreset support. This
off-by-one bug means the last 16 bytes of the rtas area can not
be used for a 16 byte save area.

It's not a serious bug, and QEMU implementation has to retain a
workaround for old kernels, but it's good to tighten it.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/platforms/pseries/ras.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Mahesh J Salgaonkar March 27, 2020, 3:51 a.m. UTC | #1
On 2020-03-25 20:34:03 Wed, Nicholas Piggin wrote:
> This was discovered developing qemu fwnmi sreset support. This
> off-by-one bug means the last 16 bytes of the rtas area can not
> be used for a 16 byte save area.
> 
> It's not a serious bug, and QEMU implementation has to retain a
> workaround for old kernels, but it's good to tighten it.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  arch/powerpc/platforms/pseries/ras.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
> index c74d5e740922..9a37bda47468 100644
> --- a/arch/powerpc/platforms/pseries/ras.c
> +++ b/arch/powerpc/platforms/pseries/ras.c
> @@ -395,10 +395,11 @@ static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
>  /*
>   * Some versions of FWNMI place the buffer inside the 4kB page starting at
>   * 0x7000. Other versions place it inside the rtas buffer. We check both.
> + * Minimum size of the buffer is 16 bytes.

Acked-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>

Thanks,
-Mahesh.

>   */
>  #define VALID_FWNMI_BUFFER(A) \
> -	((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
> -	(((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))
> +	((((A) >= 0x7000) && ((A) <= 0x8000 - 16)) || \
> +	(((A) >= rtas.base) && ((A) <= (rtas.base + rtas.size - 16))))
> 
>  static inline struct rtas_error_log *fwnmi_get_errlog(void)
>  {
> -- 
> 2.23.0
>

Patch
diff mbox series

diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index c74d5e740922..9a37bda47468 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -395,10 +395,11 @@  static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
 /*
  * Some versions of FWNMI place the buffer inside the 4kB page starting at
  * 0x7000. Other versions place it inside the rtas buffer. We check both.
+ * Minimum size of the buffer is 16 bytes.
  */
 #define VALID_FWNMI_BUFFER(A) \
-	((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
-	(((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))
+	((((A) >= 0x7000) && ((A) <= 0x8000 - 16)) || \
+	(((A) >= rtas.base) && ((A) <= (rtas.base + rtas.size - 16))))
 
 static inline struct rtas_error_log *fwnmi_get_errlog(void)
 {