[PATCH 4.19 16/50] efi/cper: use stack buffer for error record decoding

Greg Kroah-Hartman
2021-10-18T13:29:34Z

From: Ard Biesheuvel <ardb@kernel.org>

commit b3a72ca80351917cc23f9e24c35f3c3979d3c121 upstream.

Joe reports that using a statically allocated buffer for converting CPER
error records into human readable text is probably a bad idea. Even
though we are not aware of any actual issues, a stack buffer is clearly
a better choice here anyway, so let's move the buffer into the stack
frames of the two functions that refer to it.

Cc: <stable@vger.kernel.org>
Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/firmware/efi/cper.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/firmware/efi/cper.c
+++ b/drivers/firmware/efi/cper.c
@@ -37,8 +37,6 @@
#include <acpi/ghes.h>
#include <ras/ras_event.h>

-static char rcd_decode_str[CPER_REC_LEN];
-
/*
* CPER record ID need to be unique even after reboot, because record
* ID is used as index for ERST storage, while CPER records from
@@ -311,6 +309,7 @@ const char *cper_mem_err_unpack(struct t
struct cper_mem_err_compact *cmem)
{
const char *ret = trace_seq_buffer_ptr(p);
+ char rcd_decode_str[CPER_REC_LEN];

if (cper_mem_err_location(cmem, rcd_decode_str))
trace_seq_printf(p, "%s", rcd_decode_str);
@@ -325,6 +324,7 @@ static void cper_print_mem(const char *p
int len)
{
struct cper_mem_err_compact cmem;
+ char rcd_decode_str[CPER_REC_LEN];

/* Don't trust UEFI 2.1/2.2 structure with bad validation bits */
if (len == sizeof(struct cper_sec_mem_err_old) &&