From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 23 Sep 2019 18:31:33 +0000 (-0400)
Subject: Fix: lttng-crash: detect truncated files
X-Git-Tag: v2.9.13~13
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=c2684eae971ae1eb32814228ce67179439aae0a4;p=lttng-tools.git

Fix: lttng-crash: detect truncated files

Detect truncated files which size is smaller than the ring buffer
header.

This can be caused by a situation where sessiond is killed with SIGKILL
while doing a metadata regenerate command.

Without this fix, lttng-crash is killed with a "Bus error" when
encountering a truncated file.

Fixes: #1166
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-crash/lttng-crash.c b/src/bin/lttng-crash/lttng-crash.c
index 16b833dbc..ca8d30de3 100644
--- a/src/bin/lttng-crash/lttng-crash.c
+++ b/src/bin/lttng-crash/lttng-crash.c
@@ -490,7 +490,8 @@ int check_magic(const uint8_t *magic)
 }
 
 static
-int get_crash_layout(struct lttng_crash_layout *layout, int fd)
+int get_crash_layout(struct lttng_crash_layout *layout, int fd,
+		const char *input_file)
 {
 	char *map;
 	int ret = 0, unmapret;
@@ -501,7 +502,21 @@ int get_crash_layout(struct lttng_crash_layout *layout, int fd)
 	const struct crash_abi_unknown *abi;
 	uint16_t endian;
 	enum lttng_crash_type layout_type;
+	struct stat stat;
 
+	ret = fstat(fd, &stat);
+	if (ret < 0) {
+		PERROR("Failed to fstat '%s'", input_file);
+		return -1;
+	}
+	if (stat.st_size < RB_CRASH_DUMP_ABI_LEN) {
+		ERR("File '%s' truncated: file length of %" PRIi64
+				" bytes does not meet the minimal expected "
+				"length of %d bytes",
+				input_file, (int64_t) stat.st_size,
+				RB_CRASH_DUMP_ABI_LEN);
+		return -1;
+	}
 	map = mmap(NULL, RB_CRASH_DUMP_ABI_LEN, PROT_READ, MAP_PRIVATE,
 		fd, 0);
 	if (map == MAP_FAILED) {
@@ -830,7 +845,7 @@ int extract_file(int output_dir_fd, const char *output_file,
 	}
 
 	/* Query the crash ABI layout */
-	ret = get_crash_layout(&layout, fd_src);
+	ret = get_crash_layout(&layout, fd_src, input_file);
 	if (ret) {
 		goto close_src;
 	}