inputchecks: make lots of API functions check for NULL pointers

If an application accidentally provides a NULL handle pointer to the channel or sftp public functions, they now return an error instead of segfaulting.
2025-11-21 14:00:51 +03:00 · 2010-06-11 13:05:55 +02:00
parent cce6ebbee7
commit 4cf935abab
2 changed files with 163 additions and 17 deletions
--- a/src/sftp.c
+++ b/src/sftp.c
@@ -698,7 +698,8 @@ static LIBSSH2_SFTP *sftp_init(LIBSSH2_SESSION *session)
    return sftp_handle;

  sftp_init_error:
-    while (_libssh2_channel_free(session->sftpInit_channel) == LIBSSH2_ERROR_EAGAIN);
+    while (_libssh2_channel_free(session->sftpInit_channel) ==
+           LIBSSH2_ERROR_EAGAIN);
    session->sftpInit_channel = NULL;
    if (session->sftpInit_sftp) {
        LIBSSH2_FREE(session, session->sftpInit_sftp);
@@ -717,6 +718,9 @@ LIBSSH2_API LIBSSH2_SFTP *libssh2_sftp_init(LIBSSH2_SESSION *session)
 {
    LIBSSH2_SFTP *ptr;

+    if(!session)
+        return NULL;
+
    if(!(session->state & LIBSSH2_STATE_AUTHENTICATED)) {
        _libssh2_error(session, LIBSSH2_ERROR_INVAL,
                       "session not authenticated yet");
@@ -808,6 +812,8 @@ LIBSSH2_API int
 libssh2_sftp_shutdown(LIBSSH2_SFTP *sftp)
 {
    int rc;
+    if(!sftp)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, sftp->channel->session, sftp_shutdown(sftp));
    return rc;
 }
@@ -1016,6 +1022,10 @@ libssh2_sftp_open_ex(LIBSSH2_SFTP *sftp, const char *filename,
                     int open_type)
 {
    LIBSSH2_SFTP_HANDLE *hnd;
+
+    if(!sftp)
+        return NULL;
+
    BLOCK_ADJUST_ERRNO(hnd, sftp->channel->session,
                       sftp_open(sftp, filename, filename_len, flags, mode,
                                 open_type));
@@ -1192,6 +1202,8 @@ libssh2_sftp_read(LIBSSH2_SFTP_HANDLE *hnd, char *buffer,
                  size_t buffer_maxlen)
 {
    ssize_t rc;
+    if(!hnd)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, hnd->sftp->channel->session,
                 sftp_read(hnd, buffer, buffer_maxlen));
    return rc;
@@ -1363,6 +1375,8 @@ libssh2_sftp_readdir_ex(LIBSSH2_SFTP_HANDLE *hnd, char *buffer,
                        LIBSSH2_SFTP_ATTRIBUTES *attrs)
 {
    int rc;
+    if(!hnd)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, hnd->sftp->channel->session,
                 sftp_readdir(hnd, buffer, buffer_maxlen, longentry,
                              longentry_maxlen, attrs));
@@ -1470,6 +1484,8 @@ libssh2_sftp_write(LIBSSH2_SFTP_HANDLE *hnd, const char *buffer,
                   size_t count)
 {
    ssize_t rc;
+    if(!hnd)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, hnd->sftp->channel->session,
                 sftp_write(hnd, buffer, count));
    return rc;
@@ -1575,10 +1591,12 @@ static int sftp_fstat(LIBSSH2_SFTP_HANDLE *handle,
 * Get or Set stat on a file
 */
 LIBSSH2_API int
-libssh2_sftp_fstat_ex(LIBSSH2_SFTP_HANDLE * hnd,
+libssh2_sftp_fstat_ex(LIBSSH2_SFTP_HANDLE *hnd,
                      LIBSSH2_SFTP_ATTRIBUTES *attrs, int setstat)
 {
    int rc;
+    if(!hnd || !attrs)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, hnd->sftp->channel->session,
                 sftp_fstat(hnd, attrs, setstat));
    return rc;
@@ -1588,26 +1606,31 @@ libssh2_sftp_fstat_ex(LIBSSH2_SFTP_HANDLE * hnd,
 * Set the read/write pointer to an arbitrary position within the file
 */
 LIBSSH2_API void
-libssh2_sftp_seek(LIBSSH2_SFTP_HANDLE * handle, size_t offset)
+libssh2_sftp_seek(LIBSSH2_SFTP_HANDLE *handle, size_t offset)
 {
-    handle->u.file.offset = offset;
+    if(handle)
+        handle->u.file.offset = offset;
 }

 /* libssh2_sftp_seek64
 * Set the read/write pointer to an arbitrary position within the file
 */
 LIBSSH2_API void
-libssh2_sftp_seek64(LIBSSH2_SFTP_HANDLE * handle, libssh2_uint64_t offset)
+libssh2_sftp_seek64(LIBSSH2_SFTP_HANDLE *handle, libssh2_uint64_t offset)
 {
-    handle->u.file.offset = offset;
+    if(handle)
+        handle->u.file.offset = offset;
 }

 /* libssh2_sftp_tell
 * Return the current read/write pointer's offset
 */
 LIBSSH2_API size_t
-libssh2_sftp_tell(LIBSSH2_SFTP_HANDLE * handle)
+libssh2_sftp_tell(LIBSSH2_SFTP_HANDLE *handle)
 {
+    if(!handle)
+        return 0; /* no handle, no size */
+
    /* NOTE: this may very well truncate the size if it is larger than what
       size_t can hold, so libssh2_sftp_tell64() is really the function you
       should use */
@@ -1618,8 +1641,11 @@ libssh2_sftp_tell(LIBSSH2_SFTP_HANDLE * handle)
 * Return the current read/write pointer's offset
 */
 LIBSSH2_API libssh2_uint64_t
-libssh2_sftp_tell64(LIBSSH2_SFTP_HANDLE * handle)
+libssh2_sftp_tell64(LIBSSH2_SFTP_HANDLE *handle)
 {
+    if(!handle)
+        return 0; /* no handle, no size */
+
    return handle->u.file.offset;
 }

@@ -1731,6 +1757,8 @@ LIBSSH2_API int
 libssh2_sftp_close_handle(LIBSSH2_SFTP_HANDLE *hnd)
 {
    int rc;
+    if(!hnd)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, hnd->sftp->channel->session, sftp_close_handle(hnd));
    return rc;
 }
@@ -1819,6 +1847,8 @@ libssh2_sftp_unlink_ex(LIBSSH2_SFTP *sftp, const char *filename,
                       unsigned int filename_len)
 {
    int rc;
+    if(!sftp)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, sftp->channel->session,
                 sftp_unlink(sftp, filename, filename_len));
    return rc;
@@ -1949,6 +1979,8 @@ libssh2_sftp_rename_ex(LIBSSH2_SFTP *sftp, const char *source_filename,
                       unsigned int dest_filename_len, long flags)
 {
    int rc;
+    if(!sftp)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, sftp->channel->session,
                 sftp_rename(sftp, source_filename, source_filename_len,
                             dest_filename, dest_filename_len, flags));
@@ -2061,6 +2093,8 @@ LIBSSH2_API int
 libssh2_sftp_fstatvfs(LIBSSH2_SFTP_HANDLE *handle, LIBSSH2_SFTP_STATVFS *st)
 {
    int rc;
+    if(!handle || !st)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, handle->sftp->channel->session, sftp_fstatvfs(handle, st));
    return rc;
 }
@@ -2172,6 +2206,8 @@ libssh2_sftp_statvfs(LIBSSH2_SFTP *sftp, const char *path,
                     size_t path_len, LIBSSH2_SFTP_STATVFS *st)
 {
    int rc;
+    if(!sftp || !st)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, sftp->channel->session, sftp_statvfs(sftp, path, path_len,
                                                          st));
    return rc;
@@ -2277,6 +2313,8 @@ libssh2_sftp_mkdir_ex(LIBSSH2_SFTP *sftp, const char *path,
                      unsigned int path_len, long mode)
 {
    int rc;
+    if(!sftp)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, sftp->channel->session,
                 sftp_mkdir(sftp, path, path_len, mode));
    return rc;
@@ -2366,6 +2404,8 @@ libssh2_sftp_rmdir_ex(LIBSSH2_SFTP *sftp, const char *path,
                      unsigned int path_len)
 {
    int rc;
+    if(!sftp)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, sftp->channel->session,
                 sftp_rmdir(sftp, path, path_len));
    return rc;
@@ -2488,6 +2528,8 @@ libssh2_sftp_stat_ex(LIBSSH2_SFTP *sftp, const char *path,
                     LIBSSH2_SFTP_ATTRIBUTES *attrs)
 {
    int rc;
+    if(!sftp)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, sftp->channel->session,
                 sftp_stat(sftp, path, path_len, stat_type, attrs));
    return rc;
@@ -2629,6 +2671,8 @@ libssh2_sftp_symlink_ex(LIBSSH2_SFTP *sftp, const char *path,
                        unsigned int target_len, int link_type)
 {
    int rc;
+    if(!sftp)
+        return LIBSSH2_ERROR_BAD_USE;
    BLOCK_ADJUST(rc, sftp->channel->session,
                 sftp_symlink(sftp, path, path_len, target, target_len,
                              link_type));
@@ -2641,5 +2685,8 @@ libssh2_sftp_symlink_ex(LIBSSH2_SFTP *sftp, const char *path,
 LIBSSH2_API unsigned long
 libssh2_sftp_last_error(LIBSSH2_SFTP *sftp)
 {
+    if(!sftp)
+       return 0;
+
    return sftp->last_errno;
 }