On Wed, 18 Nov 2020 11:04:37 -0500
Steven Rostedt <rost...@goodmis.org> wrote:
> On Thu, 19 Nov 2020 00:35:35 +0900
> Masami Hiramatsu <mhira...@kernel.org> wrote:
>
> > 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 <torva...@linux-foundation.org>
> > Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
> > Tested-by: Chen Yu <yu.chen.s...@gmail.com>
> > ---
> > 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 52eb2bbe8966..905bfaefae35 100644
> > --- a/tools/bootconfig/main.c
> > +++ b/tools/bootconfig/main.c
> > @@ -337,6 +337,7 @@ 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;
> > @@ -394,16 +395,26 @@ static int apply_xbc(const char *path, const char
> > *xbc_path)
> > return ret;
> > }
> > /* 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:
> > @@ -411,6 +422,14 @@ static int apply_xbc(const char *path, const char
> > *xbc_path)
> > free(data);
> >
> > return ret;
> > +
> > +out_rollback:
> > + if (ftruncate(fd, stat.st_size) < 0) {
>
> If the first write fails (doesn't modify the initrd), and then this fails,
> you will show a message of: "may be corrupted. Recommend to rebuild", when
> that would not be the case. Should a test of the size be done again, to see
> if it is already the same?
Please see the above 2 write error check. You can find
if (ret < 0)
goto out;
only in the first check. (I know, it might a bit misleadable)
So, the first write is failed with error message, it doesn't call rollback.
>
> out_rollback:
> old_size = stat.st_size;
> if (stat(fd, &stat) < 0) /* Shouldn't happen, it worked once before */
> goto print_error;
>
> if (old_size < stat.st_size)
> if (ftruncate(fd, old_size) < 0)
> goto print_error;
If the old_size is current size, ftruncate must do nothing, doesn't it?
Thank you,
>
> goto out;
>
> print_error:
>
> > + 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)
>
> -- Steve
--
Masami Hiramatsu <mhira...@kernel.org>
