efi/cper: use stack buffer for error record decoding

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>

diff --git a/drivers/firmware/efi/cper.c b/drivers/firmware/efi/cper.c
index 73bdbd2..6ec8ede 100644 (file)
--- a/drivers/firmware/efi/cper.c
+++ b/drivers/firmware/efi/cper.c
@@ -25,8 +25,6 @@
 #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
@@ -312,6 +310,7 @@ const char *cper_mem_err_unpack(struct trace_seq *p,
                                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);
@@ -326,6 +325,7 @@ static void cper_print_mem(const char *pfx, const struct cper_sec_mem_err *mem,
        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) &&