[PATCH v3 1/3] tools/bootconfig: Fix to check the write failure correctly

Masami Hiramatsu
2020-11-17T09:53:28Z

Fix to check the write(2) failure including partial write
correctly and try to rollback the partial write, because
if there is no BOOTCONFIG_MAGIC string, we can not remove it.

Fixes: 85c46b78da58 ("bootconfig: Add bootconfig magic word for indicating bootconfig explicitly")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
tools/bootconfig/main.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index eb92027817a7..f7b89a50404c 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -332,6 +332,7 @@ static int delete_xbc(const char *path)

static int apply_xbc(const char *path, const char *xbc_path)
{
+ struct stat stat;
u32 size, csum;
char *buf, *data;
int ret, fd;
@@ -388,16 +389,26 @@ static int apply_xbc(const char *path, const char *xbc_path)
return fd;
}
/* TODO: Ensure the @path is initramfs/initrd image */
+ if (fstat(fd, &stat) < 0) {
+ pr_err("Failed to get the size of %s\n", path);
+ goto out;
+ }
ret = write(fd, data, size + 8);
- if (ret < 0) {
+ if (ret < size + 8) {
+ if (ret < 0)
+ ret = -errno;
pr_err("Failed to apply a boot config: %d\n", ret);
- goto out;
+ if (ret < 0)
+ goto out;
+ goto out_rollback;
}
/* Write a magic word of the bootconfig */
ret = write(fd, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);
- if (ret < 0) {
+ if (ret < BOOTCONFIG_MAGIC_LEN) {
+ if (ret < 0)
+ ret = -errno;
pr_err("Failed to apply a boot config magic: %d\n", ret);
- goto out;
+ goto out_rollback;
}
ret = 0;
out:
@@ -405,6 +416,14 @@ static int apply_xbc(const char *path, const char *xbc_path)
free(data);

return ret;
+
+out_rollback:
+ if (ftruncate(fd, stat.st_size) < 0) {
+ ret = -errno;
+ pr_err("Failed to rollback the write error: %d\n", ret);
+ pr_err("The initrd %s may be corrupted. Recommend to rebuild.\n", path);
+ }
+ goto out;
}

static int usage(void)