From: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
[ Upstream commit 942859d969de7f6f7f2659a79237a758b42782da ]
snprintf() should be given the full buffer size, not one less. And it
guarantees nul-termination, so doing it manually afterwards is
pointless.
It's even potentially harmful (though probably not in practice because
CPER_REC_LEN is 256), due to the "return how much would have been
written had the buffer been big enough" semantics. I.e., if the bank
and/or device strings are long enough that the "DIMM location ..."
output gets truncated, writing to msg[n] is a buffer overflow.
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Fixes: 3760cd20402d4 ("CPER: Adjust code flow of some functions")
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/firmware/efi/cper.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/firmware/efi/cper.c b/drivers/firmware/efi/cper.c
index c0e54396f250..dc8d2603612e 100644
--- a/drivers/firmware/efi/cper.c
+++ b/drivers/firmware/efi/cper.c
@@ -257,8 +257,7 @@ static int cper_dimm_err_location(struct cper_mem_err_compact *mem, char *msg)
if (!msg || !(mem->validation_bits & CPER_MEM_VALID_MODULE_HANDLE))
return 0;
- n = 0;
- len = CPER_REC_LEN - 1;
+ len = CPER_REC_LEN;
dmi_memdev_name(mem->mem_dev_handle, &bank, &device);
if (bank && device)
n = snprintf(msg, len, "DIMM location: %s %s ", bank, device);
@@ -267,7 +266,6 @@ static int cper_dimm_err_location(struct cper_mem_err_compact *mem, char *msg)
"DIMM location: not present. DMI handle: 0x%.4x ",
mem->mem_dev_handle);
- msg[n] = '\0';
return n;
}
--
2.30.2
