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@rasmusvillemoes.dk>
Fixes: 3760cd2040
("CPER: Adjust code flow of some functions")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -263,8 +263,7 @@ static int cper_dimm_err_location(struct cper_mem_err_compact *mem, char *msg)
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if (!msg || !(mem->validation_bits & CPER_MEM_VALID_MODULE_HANDLE))
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if (!msg || !(mem->validation_bits & CPER_MEM_VALID_MODULE_HANDLE))
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return 0;
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return 0;
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n = 0;
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len = CPER_REC_LEN;
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len = CPER_REC_LEN - 1;
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dmi_memdev_name(mem->mem_dev_handle, &bank, &device);
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dmi_memdev_name(mem->mem_dev_handle, &bank, &device);
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if (bank && device)
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if (bank && device)
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n = snprintf(msg, len, "DIMM location: %s %s ", bank, device);
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n = snprintf(msg, len, "DIMM location: %s %s ", bank, device);
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@ -273,7 +272,6 @@ static int cper_dimm_err_location(struct cper_mem_err_compact *mem, char *msg)
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"DIMM location: not present. DMI handle: 0x%.4x ",
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"DIMM location: not present. DMI handle: 0x%.4x ",
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mem->mem_dev_handle);
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mem->mem_dev_handle);
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msg[n] = '\0';
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return n;
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return n;
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}
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}
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