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Re: [Qemu-devel] [PATCH] target-ppc: kvm: Fix memory overflow issue abou
From: |
Chen Gang |
Subject: |
Re: [Qemu-devel] [PATCH] target-ppc: kvm: Fix memory overflow issue about strncat() |
Date: |
Mon, 13 Oct 2014 23:43:43 +0800 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:31.0) Gecko/20100101 Thunderbird/31.1.2 |
On 10/13/14 22:47, Alexander Graf wrote:
>
> Could you please instead rewrite it to use g_strdup_printf() rather than
> strncat()s? That way we resolve all string pitfalls automatically - and
> this code is not the fast path, so doing an extra memory allocation is ok.
>
I guess, it is a personal taste. For me, it may need additional variable
for g_strdup_printf(), and not save code lines, but *sprintf() is more
readable than str*cat().
The related code may like below (welcome any improvement for it):
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 66e7ce5..cea6a87 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -1782,7 +1782,7 @@ static int kvmppc_find_cpu_dt(char *buf, int buf_len)
* format) */
static uint64_t kvmppc_read_int_cpu_dt(const char *propname)
{
- char buf[PATH_MAX];
+ char buf[PATH_MAX], *tmp;
union {
uint32_t v32;
uint64_t v64;
@@ -1794,10 +1794,10 @@ static uint64_t kvmppc_read_int_cpu_dt(const char
*propname)
return -1;
}
- strncat(buf, "/", sizeof(buf) - strlen(buf) - 1);
- strncat(buf, propname, sizeof(buf) - strlen(buf) - 1);
+ tmp = g_strdup_printf("%s/%s", buf, propname);
- f = fopen(buf, "rb");
+ f = fopen(tmp, "rb");
+ g_free(buf);
if (!f) {
return -1;
}
For me, it is really a personal taste, so if the maintainer feels the
diff above is OK, I shall send patch v2 for it within 2 days.
Thanks.
--
Chen Gang
Open, share, and attitude like air, water, and life which God blessed