From 93ee4b7d9f0632690713aee604c49e298e634094 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Tue, 12 Feb 2019 13:09:36 -0800
Subject: [PATCH] pstore/ram: Avoid needless alloc during header write
Since the header is a fixed small maximum size, just use a stack variable
to avoid memory allocation in the write path.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
fs/pstore/ram.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index ec0e1da0596a5..c5c685589e366 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -345,19 +345,15 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record)
static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
struct pstore_record *record)
{
- char *hdr;
+ char hdr[36]; /* "===="(4), %lld(20), "."(1), %06lu(6), "-%c\n"(3) */
size_t len;
- hdr = kasprintf(GFP_ATOMIC, RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n",
+ len = scnprintf(hdr, sizeof(hdr),
+ RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n",
(time64_t)record->time.tv_sec,
record->time.tv_nsec / 1000,
record->compressed ? 'C' : 'D');
- if (WARN_ON_ONCE(!hdr))
- return 0;
-
- len = strlen(hdr);
persistent_ram_write(prz, hdr, len);
- kfree(hdr);
return len;
}
--
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