| From 8f600f2df293d539e9e9137f6f82faa1633b97c1 Mon Sep 17 00:00:00 2001 |
| From: Paul Eggert <eggert@cs.ucla.edu> |
| Date: Sat, 17 Dec 2022 20:56:29 -0800 |
| Subject: [PATCH] sed: fix symlink bufsize readlink check |
| |
| Problem reported by Hauke Mehrtens. |
| * sed/utils.c (follow_symlink): Fix typo when checking size of |
| second and later symlink, when that symlink is so large that it |
| does not fit into the buffer. Although the bug is not a buffer |
| overflow, it does cause sed to mishandle the symlink. |
| * testsuite/follow-symlinks.sh: Test for the bug. |
| --- |
| sed/utils.c | 2 +- |
| testsuite/follow-symlinks.sh | 13 +++++++++++++ |
| 3 files changed, 18 insertions(+), 1 deletion(-) |
| |
| --- a/sed/utils.c |
| +++ b/sed/utils.c |
| @@ -345,7 +345,7 @@ follow_symlink (const char *fname) |
| while ((linklen = (buf_used < buf_size |
| ? readlink (fn, buf + buf_used, buf_size - buf_used) |
| : 0)) |
| - == buf_size) |
| + == buf_size - buf_used) |
| { |
| buf = xpalloc (buf, &buf_size, 1, SSIZE_IDX_MAX, 1); |
| if (num_links) |
| --- a/testsuite/follow-symlinks.sh |
| +++ b/testsuite/follow-symlinks.sh |
| @@ -73,4 +73,17 @@ compare_ exp-la-abs out-la-abs || fail=1 |
| ln -s la-loop la-loop || framework_failure_ |
| sed --follow-symlinks -i s/a/b/ la-loop && fail=1 |
| |
| +# symlink of length 128 |
| +long=d/ |
| +for i in 2 3 4 5 6 7; do |
| + long=$long$long |
| +done |
| +dir=${long%/d/} |
| +file=$dir/xx |
| +mkdir -p $dir && |
| +echo x >$file && |
| +ln -s $file yy && |
| +ln -s yy xx || framework_failure_ |
| +sed -i --follow-symlinks s/x/y/ xx || fail=1 |
| + |
| Exit $fail |