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LoadPin: Annotate struct dm_verity_loadpin_trusted_root_digest with __counted_by

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Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct dm_verity_loadpin_trusted_root_digest.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: dm-devel@redhat.com
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
Link: https://lore.kernel.org/r/20230817235955.never.762-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2023-08-17 16:59:56 -07:00
parent 76903a9648
commit 5f536ac6a5
2 changed files with 2 additions and 3 deletions
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2
include/linux/dm-verity-loadpin.h
View File

@ -12,7 +12,7 @@ extern struct list_head dm_verity_loadpin_trusted_root_digests;
struct dm_verity_loadpin_trusted_root_digest {
struct list_head node;
unsigned int len;
u8 data[];
u8 data[] __counted_by(len);
};
#if IS_ENABLED(CONFIG_SECURITY_LOADPIN_VERITY)

3
security/loadpin/loadpin.c
View File

@ -336,6 +336,7 @@ static int read_trusted_verity_root_digests(unsigned int fd)
rc = -ENOMEM;
goto err;
}
trd->len = len;
if (hex2bin(trd->data, d, len)) {
kfree(trd);
@ -343,8 +344,6 @@ static int read_trusted_verity_root_digests(unsigned int fd)
goto err;
}
trd->len = len;
list_add_tail(&trd->node, &dm_verity_loadpin_trusted_root_digests);
}