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alistair23-linux/drivers/misc/altera-stapl
Daniel Axtens 886a8fb13d altera-stapl: altera_get_note: prevent write beyond end of 'key'
[ Upstream commit 3745488e9d ]

altera_get_note is called from altera_init, where key is kzalloc(33).

When the allocation functions are annotated to allow the compiler to see
the sizes of objects, and with FORTIFY_SOURCE, we see:

In file included from drivers/misc/altera-stapl/altera.c:14:0:
In function ‘strlcpy’,
    inlined from ‘altera_init’ at drivers/misc/altera-stapl/altera.c:2189:5:
include/linux/string.h:378:4: error: call to ‘__write_overflow’ declared with attribute error: detected write beyond size of object passed as 1st parameter
    __write_overflow();
    ^~~~~~~~~~~~~~~~~~

That refers to this code in altera_get_note:

    if (key != NULL)
            strlcpy(key, &p[note_strings +
                            get_unaligned_be32(
                            &p[note_table + (8 * i)])],
                    length);

The error triggers because the length of 'key' is 33, but the copy
uses length supplied as the 'length' parameter, which is always
256. Split the size parameter into key_len and val_len, and use the
appropriate length depending on what is being copied.

Detected by compiler error, only compile-tested.

Cc: "Igor M. Liplianin" <liplianin@netup.ru>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Link: https://lore.kernel.org/r/20200120074344.504-2-dja@axtens.net
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/202002251042.D898E67AC@keescook
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-25 08:25:47 +01:00
..
Kconfig Merge 5.2-rc4 into char-misc-next 2019-06-09 09:11:21 +02:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
altera-comp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
altera-exprt.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
altera-jtag.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
altera-jtag.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
altera-lpt.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
altera.c altera-stapl: altera_get_note: prevent write beyond end of 'key' 2020-03-25 08:25:47 +01:00