From 5cb808572c23db828f2ac35c0c1e7088aef5ec03 Mon Sep 17 00:00:00 2001 From: Mahesh Salgaonkar Date: Wed, 4 Jul 2018 23:27:02 +0530 Subject: powerpc/pseries: Avoid using the size greater than RTAS_ERROR_LOG_MAX. [ Upstream commit 74e96bf44f430cf7a01de19ba6cf49b361cdfd6e ] 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 Signed-off-by: Mahesh Salgaonkar Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/platforms/pseries/ras.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c index 34989ce43147..8799d8a83d56 100644 --- a/arch/powerpc/platforms/pseries/ras.c +++ b/arch/powerpc/platforms/pseries/ras.c @@ -357,7 +357,7 @@ 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; -- cgit v1.2.3