This is a note to let you know that I've just added the patch titled
efi: cper: fix snprintf() use in cper_dimm_err_location()
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
efi-cper-fix-snprintf-use-in-cper_dimm_err_location.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9382d26556b355ff82464fc677249e8181d2233c
Author: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 21 21:46:36 2021 +0200
efi: cper: fix snprintf() use in cper_dimm_err_location()
[ 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>
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;
}
