[PATCH 5.17 060/158] crypto: qcom-rng - fix infinite loop on requests not multiple of WORD_SZ

Greg Kroah-Hartman
2022-05-23T17:58:49Z

From: Ondrej Mosnacek <omosnace@redhat.com>

commit 16287397ec5c08aa58db6acf7dbc55470d78087d upstream.

The commit referenced in the Fixes tag removed the 'break' from the else
branch in qcom_rng_read(), causing an infinite loop whenever 'max' is
not a multiple of WORD_SZ. This can be reproduced e.g. by running:

kcapi-rng -b 67 >/dev/null

There are many ways to fix this without adding back the 'break', but
they all seem more awkward than simply adding it back, so do just that.

Tested on a machine with Qualcomm Amberwing processor.

Fixes: a680b1832ced ("crypto: qcom-rng - ensure buffer for generate is completely filled")
Cc: stable@vger.kernel.org
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Brian Masney <bmasney@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/crypto/qcom-rng.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/crypto/qcom-rng.c
+++ b/drivers/crypto/qcom-rng.c
@@ -65,6 +65,7 @@ static int qcom_rng_read(struct qcom_rng
} else {
/* copy only remaining bytes */
memcpy(data, &val, max - currsize);
+ break;
}
} while (currsize < max);