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<p class="MsoNormal"><span lang="EN-US">1.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">As shown in the definition of nl_recv, its return value is of INT type.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">int nl_recv(struct nl_handle *handle, struct sockaddr_nl *nla,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> unsigned char **buf, struct ucred **creds)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">However, in function virNetlinkCommand, it uses an unsigned int param,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">respbuflen, to receive its return value. Thus, the branch "*respbuflen < 0"<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">is unreachable, negative return values are handled incorrectly.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">2.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">It's said in nl_recv's description that "The caller is responsible for<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">freeing the buffer allocated * in \c *buf if a positive value is returned."<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">which means, we needn't to free it in case it fails.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Additionally, nl_recv has a BUG in handling buf: in the error branch, it frees<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">the buf, but didn't set it to NULL. Freeing it outside in the caller function<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">will cause double free.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thus, we set but(resp) to NULL if nl_recv fails.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Signed-off-by: Zhang Bo <oscar.zhangbo@huawei.com><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">---<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">src/util/virnetlink.c | 8 ++++++--<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">1 file changed, 6 insertions(+), 2 deletions(-)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">diff --git a/src/util/virnetlink.c b/src/util/virnetlink.c<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">index 0cf18f2..1a09567 100644<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">--- a/src/util/virnetlink.c<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">+++ b/src/util/virnetlink.c<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">@@ -192,6 +192,7 @@ int virNetlinkCommand(struct nl_msg *nl_msg,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> int n;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> struct nlmsghdr *nlmsg = nlmsg_hdr(nl_msg);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> virNetlinkHandle *nlhandle = NULL;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">+ int length = 0;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> if (protocol >= MAX_LINKS) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> virReportSystemError(EINVAL,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">@@ -257,12 +258,15 @@ int virNetlinkCommand(struct nl_msg *nl_msg,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> goto error;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">- *respbuflen = nl_recv(nlhandle, &nladdr,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">- (unsigned char **)resp, NULL);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">+ length = nl_recv(nlhandle, &nladdr,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">+ (unsigned char **)resp, NULL);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">- if (*respbuflen <= 0) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">+ if (length <= 0) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> virReportSystemError(errno,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> "%s", _("nl_recv failed"));<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">+ *resp = NULL;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> rc = -1;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">+ } else {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">+ *respbuflen = length;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> error:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> if (rc == -1) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">-- <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">1.7.12.4<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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