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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Joe Perches <joe@perches.com>,
        Ard Biesheuvel <ardb@kernel.org>
Subject: [PATCH 5.4 23/69] efi/cper: use stack buffer for error record decoding
Date:   Mon, 18 Oct 2021 15:24:21 +0200
Message-Id: <20211018132330.229106611@linuxfoundation.org>
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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
@@ -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
@@ -299,6 +297,7 @@ 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);
@@ -313,6 +312,7 @@ 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) &&