[lttng-dev] [PATCH lttng-tools] Fix: lttng-crash: detect truncated files

[Mathieu Desnoyers]

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 at efficios.com>
---
 src/bin/lttng-crash/lttng-crash.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/bin/lttng-crash/lttng-crash.c b/src/bin/lttng-crash/lttng-crash.c
index 298ed71a..47358df9 100644
--- a/src/bin/lttng-crash/lttng-crash.c
+++ b/src/bin/lttng-crash/lttng-crash.c
@@ -498,7 +498,8 @@ 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;
@@ -509,7 +510,17 @@ 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("fstat");
+		return -1;
+	}
+	if (stat.st_size < RB_CRASH_DUMP_ABI_LEN) {
+		ERR("File: '%s' truncated", input_file);
+		return -1;
+	}
 	map = mmap(NULL, RB_CRASH_DUMP_ABI_LEN, PROT_READ, MAP_PRIVATE,
 		fd, 0);
 	if (map == MAP_FAILED) {
@@ -838,7 +849,7 @@ 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;
 	}
-- 
2.11.0