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EFI/CPER: don't dump the entire memory region

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The current logic at cper_print_fw_err() doesn't check if the
error record length is big enough to handle offset. On a bad firmware,
if the ofset is above the actual record, length -= offset will
underflow, making it dump the entire memory.

The end result can be:

 - the logic taking a lot of time dumping large regions of memory;
 - data disclosure due to the memory dumps;
 - an OOPS, if it tries to dump an unmapped memory region.

Fix it by checking if the section length is too small before doing
a hex dump.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
[ rjw: Subject tweaks ]
Link: https://patch.msgid.link/1752b5ba63a3e2f148ddee813b36c996cc617e86.1767871950.git.mchehab+huawei@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Mauro Carvalho Chehab 2026-01-08 12:35:06 +01:00 • committed by Rafael J. Wysocki
parent fa2408a24f
commit 55cc6fe571
1 changed files with 5 additions and 0 deletions
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5
drivers/firmware/efi/cper.c
View file

@ -560,6 +560,11 @@ static void cper_print_fw_err(const char *pfx,
} else {
offset = sizeof(*fw_err);
}
if (offset > length) {
printk("%s""error section length is too small: offset=%d, length=%d\n",
pfx, offset, length);
return;
}
buf += offset;
length -= offset;