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Message-ID: <3ac3fd6a-755e-4829-bc56-234f5b0f35e4@web.de>
Date: Sat, 12 Oct 2024 17:10:26 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: linux-crypto@...r.kernel.org, kernel-janitors@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Herbert Xu <herbert@...dor.apana.org.au>,
Peter Zijlstra <peterz@...radead.org>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 3/3] lib/digsig: Use scope-based resource management for
two variables in digsig_verify_rsa()
From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Sat, 12 Oct 2024 15:28:22 +0200
Scope-based resource management became supported for some
programming interfaces by contributions of Peter Zijlstra on 2023-05-26.
See also the commit 54da6a0924311c7cf5015533991e44fb8eb12773 ("locking:
Introduce __cleanup() based infrastructure").
* Thus use the attribute “__free(kfree)”.
* Reduce the scopes for the local variables “out1” and “p”.
* Omit explicit kfree() calls accordingly.
* Add a jump target.
Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
V3:
Further adjustments were provided for the demonstration of an evolving
programming interface.
lib/digsig.c | 87 +++++++++++++++++++++++++---------------------------
1 file changed, 42 insertions(+), 45 deletions(-)
diff --git a/lib/digsig.c b/lib/digsig.c
index 2481120094ab..1a24677af643 100644
--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -73,10 +73,9 @@ static int digsig_verify_rsa(struct key *key,
unsigned long mlen, mblen;
unsigned int l;
int head, i;
- unsigned char *out1 = NULL;
const char *m;
MPI pkey[2];
- uint8_t *p, *datap;
+ uint8_t *datap;
const uint8_t *endp;
const struct user_key_payload *ukp;
struct pubkey_hdr *pkh;
@@ -126,58 +125,56 @@ static int digsig_verify_rsa(struct key *key,
}
err = -ENOMEM;
-
- out1 = kzalloc(mlen, GFP_KERNEL);
- if (!out1)
- goto free_keys;
-
{
- unsigned int nret = siglen;
- MPI in __free(mpi_free) = mpi_read_from_buffer(sig, &nret);
-
- if (IS_ERR(in)) {
- err = PTR_ERR(in);
- goto in_exit;
- }
+ unsigned char *out1 __free(kfree) = kzalloc(mlen, GFP_KERNEL);
+ if (out1)
{
- MPI res __free(mpi_free) = mpi_alloc(mpi_get_nlimbs(in) * 2);
-
- if (!res)
- goto res_exit;
-
- err = mpi_powm(res, in, pkey[1], pkey[0]);
- if (err)
- goto res_exit;
-
- if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) {
- err = -EINVAL;
- goto res_exit;
- }
+ unsigned int nret = siglen;
+ MPI in __free(mpi_free) = mpi_read_from_buffer(sig, &nret);
- p = mpi_get_buffer(res, &l, NULL);
- if (!p) {
- err = -EINVAL;
- goto res_exit;
+ if (IS_ERR(in)) {
+ err = PTR_ERR(in);
+ goto in_exit;
}
- len = mlen;
- head = len - l;
- memset(out1, 0, head);
- memcpy(out1 + head, p, l);
-
- kfree(p);
-
- m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len);
-
- if (!m || len != hlen || memcmp(m, h, hlen))
- err = -EINVAL;
+ {
+ MPI res __free(mpi_free) = mpi_alloc(mpi_get_nlimbs(in) * 2);
+
+ if (!res)
+ goto res_exit;
+
+ err = mpi_powm(res, in, pkey[1], pkey[0]);
+ if (err)
+ goto res_exit;
+
+ if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) {
+ err = -EINVAL;
+ goto res_exit;
+ }
+
+ {
+ uint8_t *p __free(kfree) = mpi_get_buffer(res, &l, NULL);
+
+ if (!p) {
+ err = -EINVAL;
+ goto p_exit;
+ }
+
+ len = mlen;
+ head = len - l;
+ memset(out1, 0, head);
+ memcpy(out1 + head, p, l);
+ m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len);
+ if (!m || len != hlen || memcmp(m, h, hlen))
+ err = -EINVAL;
+p_exit:
+ }
res_exit:
- }
+ }
in_exit:
+ }
}
-
- kfree(out1);
free_keys:
while (--i >= 0)
mpi_free(pkey[i]);
--
2.46.1
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