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curl_schannel: Improvements to memory re-allocation strategy

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- do not grow memory by doubling its size
- do not leak previously allocated memory if reallocation fails
- replace while-loop with a single check to make sure
  that the requested amount of data fits into the buffer

Bug: http://curl.haxx.se/bug/view.cgi?id=1450
Reported-by: Warren Menzer
This commit is contained in:
Marc Hoersken 2014-12-14 17:27:20 +01:00
parent 125f655131
commit 212e3e26bc
2 changed files with 42 additions and 17 deletions
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58
lib/vtls/curl_schannel.c
View File

@ -294,6 +294,8 @@ schannel_connect_step2(struct connectdata *conn, int sockindex)
ssize_t nread = -1, written = -1;
struct SessionHandle *data = conn->data;
struct ssl_connect_data *connssl = &conn->ssl[sockindex];
unsigned char *reallocated_buffer;
size_t reallocated_length;
SecBuffer outbuf[2];
SecBufferDesc outbuf_desc;
SecBuffer inbuf[2];
@ -326,14 +328,19 @@ schannel_connect_step2(struct connectdata *conn, int sockindex)
if(connssl->encdata_length - connssl->encdata_offset <
CURL_SCHANNEL_BUFFER_FREE_SIZE) {
/* increase internal encrypted data buffer */
connssl->encdata_length *= CURL_SCHANNEL_BUFFER_STEP_FACTOR;
connssl->encdata_buffer = realloc(connssl->encdata_buffer,
connssl->encdata_length);
reallocated_length = connssl->encdata_offset +
CURL_SCHANNEL_BUFFER_FREE_SIZE;
reallocated_buffer = realloc(connssl->encdata_buffer,
reallocated_length);
if(connssl->encdata_buffer == NULL) {
if(reallocated_buffer == NULL) {
failf(data, "schannel: unable to re-allocate memory");
return CURLE_OUT_OF_MEMORY;
}
else {
connssl->encdata_buffer = reallocated_buffer;
connssl->encdata_length = reallocated_length;
}
}
for(;;) {
@ -828,6 +835,8 @@ schannel_recv(struct connectdata *conn, int sockindex,
CURLcode retcode;
struct SessionHandle *data = conn->data;
struct ssl_connect_data *connssl = &conn->ssl[sockindex];
unsigned char *reallocated_buffer;
size_t reallocated_length;
bool done = FALSE;
SecBuffer inbuf[4];
SecBufferDesc inbuf_desc;
@ -849,18 +858,27 @@ schannel_recv(struct connectdata *conn, int sockindex,
}
/* increase buffer in order to fit the requested amount of data */
while(connssl->encdata_length - connssl->encdata_offset <
CURL_SCHANNEL_BUFFER_FREE_SIZE || connssl->encdata_length < len) {
if(connssl->encdata_length - connssl->encdata_offset <
CURL_SCHANNEL_BUFFER_FREE_SIZE || connssl->encdata_length < len) {
/* increase internal encrypted data buffer */
connssl->encdata_length *= CURL_SCHANNEL_BUFFER_STEP_FACTOR;
connssl->encdata_buffer = realloc(connssl->encdata_buffer,
connssl->encdata_length);
reallocated_length = connssl->encdata_offset +
CURL_SCHANNEL_BUFFER_FREE_SIZE;
/* make sure that the requested amount of data fits */
if(reallocated_length < len) {
reallocated_length = len;
}
reallocated_buffer = realloc(connssl->encdata_buffer,
reallocated_length);
if(connssl->encdata_buffer == NULL) {
if(reallocated_buffer == NULL) {
failf(data, "schannel: unable to re-allocate memory");
*err = CURLE_OUT_OF_MEMORY;
return -1;
}
else {
connssl->encdata_buffer = reallocated_buffer;
connssl->encdata_length = reallocated_length;
}
}
/* read encrypted data from socket */
@ -924,18 +942,26 @@ schannel_recv(struct connectdata *conn, int sockindex,
/* increase buffer in order to fit the received amount of data */
size = inbuf[1].cbBuffer > CURL_SCHANNEL_BUFFER_FREE_SIZE ?
inbuf[1].cbBuffer : CURL_SCHANNEL_BUFFER_FREE_SIZE;
while(connssl->decdata_length - connssl->decdata_offset < size ||
connssl->decdata_length < len) {
if(connssl->decdata_length - connssl->decdata_offset < size ||
connssl->decdata_length < len) {
/* increase internal decrypted data buffer */
connssl->decdata_length *= CURL_SCHANNEL_BUFFER_STEP_FACTOR;
connssl->decdata_buffer = realloc(connssl->decdata_buffer,
connssl->decdata_length);
reallocated_length = connssl->decdata_offset + size;
/* make sure that the requested amount of data fits */
if(reallocated_length < len) {
reallocated_length = len;
}
reallocated_buffer = realloc(connssl->decdata_buffer,
reallocated_length);
if(connssl->decdata_buffer == NULL) {
if(reallocated_buffer == NULL) {
failf(data, "schannel: unable to re-allocate memory");
*err = CURLE_OUT_OF_MEMORY;
return -1;
}
else {
connssl->decdata_buffer = reallocated_buffer;
connssl->decdata_length = reallocated_length;
}
}
/* copy decrypted data to internal buffer */

1
lib/vtls/curl_schannel.h
View File

@ -95,7 +95,6 @@
#define CURL_SCHANNEL_BUFFER_INIT_SIZE 4096
#define CURL_SCHANNEL_BUFFER_FREE_SIZE 1024
#define CURL_SCHANNEL_BUFFER_STEP_FACTOR 2
CURLcode Curl_schannel_connect(struct connectdata *conn, int sockindex);