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Fixes double free in buffer cleanup. Ensures buffer is freed correctly. #717

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merged 1 commit into from
Aug 23, 2023
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Fixes double free in buffer cleanup. Ensures buffer is freed correctly. #717

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44 changes: 21 additions & 23 deletions programs/ziti-edge-tunnel/netif_driver/linux/resolvers.c
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Original file line number Diff line number Diff line change
Expand Up @@ -420,25 +420,25 @@ void dns_update_resolvconf(const char *tun, unsigned int ifindex, const char *ad

static bool make_copy(const char *src, const char *dst) {

uv_fs_t *req = (uv_fs_t *)malloc(sizeof(uv_fs_t));
uv_fs_t req = {0};

ZITI_LOG(INFO, "attempting copy of: %s", src);

int ret = uv_fs_copyfile(uv_default_loop(), req, src, dst, UV_FS_COPYFILE_EXCL, NULL);
int ret = uv_fs_copyfile(uv_default_loop(), &req, src, dst, UV_FS_COPYFILE_EXCL, NULL);

if (req->result < 0) {
if (req->result == UV_EEXIST) {
ZITI_LOG(DEBUG, "%s has already been copied", req->path);
if (req.result < 0) {
if (req.result == UV_EEXIST) {
ZITI_LOG(DEBUG, "%s has already been copied", req.path);
} else {
ZITI_LOG(WARN, "could not create copy[%s]: %s", req->new_path, uv_strerror(req->result));
uv_fs_req_cleanup(req);
ZITI_LOG(WARN, "could not create copy[%s]: %s", req.new_path, uv_strerror(req.result));
uv_fs_req_cleanup(&req);
return false;
}
}

ZITI_LOG(INFO, "copy successful: %s", req->new_path);
ZITI_LOG(INFO, "copy successful: %s", req.new_path);

uv_fs_req_cleanup(req);
uv_fs_req_cleanup(&req);

return true;
}
Expand Down Expand Up @@ -480,15 +480,15 @@ void dns_update_etc_resolv(const char *tun, unsigned int ifindex, const char *ad
return;
}

char *buffer = NULL;
_cleanup_(cleanup_bufferp) char *buffer = NULL;
size_t buffer_size;
ssize_t line_size;
off_t match_start_offset = -1;

while((line_size = getline(&buffer, &buffer_size, file)) != -1) {
if(strstr(buffer, match) != NULL) {
if(strstr(buffer, replace) != NULL) {
ZITI_LOG(TRACE, "ziti nameserver is already in %s", RESOLV_CONF_FILE);
ZITI_LOG(DEBUG, "ziti nameserver is already in %s", RESOLV_CONF_FILE);
return;
}
match_start_offset = ftell(file) - line_size;
Expand Down Expand Up @@ -537,11 +537,8 @@ void dns_update_etc_resolv(const char *tun, unsigned int ifindex, const char *ad
CLEANUP_ETC_RESOLV();
}

// Handle case in which realloc moves the memory block
// and calls free()
if (rptr != replace) {
replace = NULL;
}
// prevent double free() when cleanup_bufferp() is called
replace = NULL;

strcat(rptr, remaining_content);

Expand All @@ -560,16 +557,17 @@ void dns_update_etc_resolv(const char *tun, unsigned int ifindex, const char *ad
CLEANUP_ETC_RESOLV();
}
}
ZITI_LOG(DEBUG, "Added ziti DNS resolver to %s", RESOLV_CONF_FILE);

return;
} else {
// If no nameserver directives to prepend, just append to the file.
if (fputs(replace, file) == EOF) {
ZITI_LOG(ERROR, "EOF received while appending to: %s", RESOLV_CONF_FILE);
CLEANUP_ETC_RESOLV();
}
}

// If no nameserver directives to prepend, just append to the file.
if (fputs(replace, file) == EOF) {
ZITI_LOG(ERROR, "EOF received while appending to: %s", RESOLV_CONF_FILE);
CLEANUP_ETC_RESOLV();
}
ZITI_LOG(DEBUG, "Added ziti DNS resolver to %s", RESOLV_CONF_FILE);

return;
}

Expand Down
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