From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Mon, 25 Feb 2019 18:55:03 +0000 (+0200)
Subject: fs-posix: fs_read_stream() - Don't close file's fd
X-Git-Tag: 2.3.6~123
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ae72b863882cea401fa67ddb0be4549cba8b83de;p=thirdparty%2Fdovecot%2Fcore.git

fs-posix: fs_read_stream() - Don't close file's fd

This is especially important with newly created files, because they may
still be accessed after reading. The next file access attempt after
fs_read_stream() might cause the file to be recreated and crash.

Fixes:
Panic: file fs-posix.c: line 252 (fs_posix_create): assertion failed: (file->temp_path == NULL)
---

diff --git a/src/lib-fs/fs-posix.c b/src/lib-fs/fs-posix.c
index 20531db156..194fdec1e5 100644
--- a/src/lib-fs/fs-posix.c
+++ b/src/lib-fs/fs-posix.c
@@ -444,12 +444,18 @@ fs_posix_read_stream(struct fs_file *_file, size_t max_buffer_size)
 {
 	struct posix_fs_file *file = (struct posix_fs_file *)_file;
 	struct istream *input;
+	int fd_dup;
 
 	if (fs_posix_open_for_read(file) < 0)
 		input = i_stream_create_error_str(errno, "%s", fs_last_error(_file->fs));
+	else if ((fd_dup = dup(file->fd)) == -1)
+		input = i_stream_create_error_str(errno, "dup() failed: %m");
 	else {
-		/* the stream could live even after the fs_file */
-		input = i_stream_create_fd_autoclose(&file->fd, max_buffer_size);
+		/* The stream could live even after the fs_file.
+		   Don't use file->fd directly, because the fd may still be
+		   used for other purposes. It's especially important for files
+		   that were just created. */
+		input = i_stream_create_fd_autoclose(&fd_dup, max_buffer_size);
 	}
 	i_stream_set_name(input, file->full_path);
 	return input;