Re: [PATCH] bcachefs: avoid copy from NULL printbuf

[Hongbo Li]

On 2024/9/24 10:52, David Disseldorp wrote:
printbuf.buf may be NULL if allocation_failure is set. Check for this
prior to using it as a seq_puts() source.

Fixes: fa8e94faeece1 ("bcachefs: Heap allocate printbufs")
Signed-off-by: David Disseldorp <dd...@suse.de>
---
test test

  fs/bcachefs/fs.c | 7 +++++--
  1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index 1aee5bafaae54..6e270bf24591d 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -1931,13 +1931,16 @@ static int bch2_show_options(struct seq_file *seq, 
struct dentry *root)
  {
        struct bch_fs *c = root->d_sb->s_fs_info;
        struct printbuf buf = PRINTBUF;
+       int ret = 0;
  
  	bch2_opts_to_text(&buf, c->opts, c, c->disk_sb.sb,
                          OPT_MOUNT, OPT_HIDDEN, OPT_SHOW_MOUNT_STYLE);
        printbuf_nul_terminate(&buf);
-       seq_puts(seq, buf.buf);
+       if (buf.allocation_failure)
+               ret = -ENOMEM;
+       else
+               seq_puts(seq, buf.buf);
  
May I fix here in the last patch "bcachefs: fix incorrect show_options 
results" in v2, and add you as co-author?

Thanks,
Hongbo

-       int ret = buf.allocation_failure ? -ENOMEM : 0;
        printbuf_exit(&buf);
        return ret;
  }