KEYS: asymmetric: Copy sig and digest in public_key_verify_signature()

Commit ac4e97abce9b8 ("scatterlist: sg_set_buf() argument must be in linear
mapping") checks that both the signature and the digest reside in the
linear mapping area.

However, more recently commit ba14a194a434c ("fork: Add generic vmalloced
stack support") made it possible to move the stack in the vmalloc area,
which is not contiguous, and thus not suitable for sg_set_buf() which needs
adjacent pages.

Always make a copy of the signature and digest in the same buffer used to
store the key and its parameters, and pass them to sg_init_one(). Prefer it
to conditionally doing the copy if necessary, to keep the code simple. The
buffer allocated with kmalloc() is in the linear mapping area.

Cc: [email protected] # 4.9.x
Fixes: ba14a194a434 ("fork: Add generic vmalloced stack support")
Link: https://lore.kernel.org/linux-integrity/[email protected]/
Suggested-by: Eric Biggers <[email protected]>
Signed-off-by: Roberto Sassu <[email protected]>
Reviewed-by: Eric Biggers <[email protected]>
Tested-by: Stefan Berger <[email protected]>

0 files changed, 0 insertions, 0 deletions