[v7,1/9] powerpc/pseries: Avoid using the size greater than RTAS_ERROR_LOG_MAX.

Message ID 153365136196.14256.9927143064547021494.stgit@jupiter.in.ibm.com
State Changes Requested
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Series
  • powerpc/pseries: Machine check handler improvements.
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snowpatch_ozlabs/apply_patch fail Failed to apply to any branch

Commit Message

Mahesh J Salgaonkar Aug. 7, 2018, 2:16 p.m.
From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>

The global mce data buffer that used to copy rtas error log is of 2048
(RTAS_ERROR_LOG_MAX) bytes in size. Before the copy we read
extended_log_length from rtas error log header, then use max of
extended_log_length and RTAS_ERROR_LOG_MAX as a size of data to be copied.
Ideally the platform (phyp) will never send extended error log with
size > 2048. But if that happens, then we have a risk of buffer overrun
and corruption. Fix this by using min_t instead.

Fixes: d368514c3097 ("powerpc: Fix corruption when grabbing FWNMI data")
Reported-by: Michal Suchanek <msuchanek@suse.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/pseries/ras.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index 5e1ef9150182..ef104144d4bc 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -371,7 +371,7 @@  static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
 		int len, error_log_length;
 
 		error_log_length = 8 + rtas_error_extended_log_length(h);
-		len = max_t(int, error_log_length, RTAS_ERROR_LOG_MAX);
+		len = min_t(int, error_log_length, RTAS_ERROR_LOG_MAX);
 		memset(global_mce_data_buf, 0, RTAS_ERROR_LOG_MAX);
 		memcpy(global_mce_data_buf, h, len);
 		errhdr = (struct rtas_error_log *)global_mce_data_buf;