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ovl: Use "buf" flexible array for memcpy() destination

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The "buf" flexible array needs to be the memcpy() destination to avoid
false positive run-time warning from the recent FORTIFY_SOURCE
hardening:

  memcpy: detected field-spanning write (size 93) of single field "&fh->fb"
  at fs/overlayfs/export.c:799 (size 21)

Reported-by: syzbot+9d14351a171d0d1c7955@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/000000000000763a6c05e95a5985@google.com/
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Kees Cook 2022-09-24 00:33:15 -07:00 committed by Miklos Szeredi
parent 456b59e757
commit cf8aa9bf97
2 changed files with 2 additions and 2 deletions
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2
fs/overlayfs/export.c
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@ -796,7 +796,7 @@ static struct ovl_fh *ovl_fid_to_fh(struct fid *fid, int buflen, int fh_type)
return ERR_PTR(-ENOMEM);
/* Copy unaligned inner fh into aligned buffer */
memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET);
memcpy(fh->buf, fid, buflen - OVL_FH_WIRE_OFFSET);
return fh;
}

2
fs/overlayfs/overlayfs.h
View file

@ -108,7 +108,7 @@ struct ovl_fh {
u8 padding[3]; /* make sure fb.fid is 32bit aligned */
union {
struct ovl_fb fb;
u8 buf[0];
DECLARE_FLEX_ARRAY(u8, buf);
};
} __packed;