patch 9.1.1567: crash when using inline diff mode

Problem:  Crash when using inline diff mode
          (Ilya Grigoriev)
Solution: Set tp_diffbuf to NULL when skipping a diff block
          (Yee Cheng Chin).

Fix an array out of bounds crash when using diffopt+=inline:char when 4
or more buffers are being diff'ed. This happens when one of the blocks
is empty. The inline highlight logic skips using that buffer's block,
but when another buffer is used later and calls diff_read() to merge the
diff blocks together, it could erroneously consider the empty block's
diff info which has not been initialized, leaving to diff numbers that
are invalid. Later on the diff num is used without bounds checking which
leads to the crash.

Fix this by making sure to unset tp_diffbuf to NULL when we skip a
block, so diff_read() will not consider this buffer to be used within
inline diff. Also, add more bounds checking just to be safe.

closes: #17805

Signed-off-by: Yee Cheng Chin <ychin.git@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

diff --git a/src/diff.c b/src/diff.c
index 21fb7483818107fe558bd1fada83460832d5b44b..d86dbf153033409e416bde1e138c5f9819e1b0b4 100644 (file)
--- a/src/diff.c
+++ b/src/diff.c
@@ -3391,6 +3391,11 @@ diff_find_change_inline_diff(
     diff_T     *orig_diff = curtab->tp_first_diff;
     curtab->tp_first_diff = NULL;
 
+    // diff_read() also uses curtab->tp_diffbuf to determine what's an active
+    // buffer
+    buf_T      *(orig_diffbuf[DB_COUNT]);
+    memcpy(orig_diffbuf, curtab->tp_diffbuf, sizeof(orig_diffbuf));
+
     // Buffers to populate mmfile 1/2 that would be passed to xdiff as memory
     // files. Use a grow array as it is not obvious how much exact space we
     // need.
@@ -3412,7 +3417,12 @@ diff_find_change_inline_diff(
            continue; // skip buffer that isn't loaded
 
        if (dp->df_count[i] == 0)
-           continue; // skip buffer that don't have any texts in this block
+       {
+           // skip buffers that don't have any texts in this block so we don't
+           // end up marking the entire block as modified in multi-buffer diff
+           curtab->tp_diffbuf[i] = NULL;
+           continue;
+       }
 
        if (file1_idx == -1)
            file1_idx = i;
@@ -3626,7 +3636,7 @@ diff_find_change_inline_diff(
        CLEAR_FIELD(change);
        for (int i = 0; i < DB_COUNT; i++)
        {
-           if (new_diff->df_lnum[i] == 0)
+           if (new_diff->df_lnum[i] <= 0) // should never be < 0. Checking just for safety.
                continue;
            linenr_T diff_lnum = new_diff->df_lnum[i] - 1; // use zero-index
            linenr_T diff_lnum_end = diff_lnum + new_diff->df_count[i];
@@ -3675,6 +3685,7 @@ done:
 
     diff_clear(curtab);
     curtab->tp_first_diff = orig_diff;
+    memcpy(curtab->tp_diffbuf, orig_diffbuf, sizeof(orig_diffbuf));
 
     ga_clear(&file1_str);
     ga_clear(&file2_str);

diff --git a/src/testdir/dumps/Test_diff_inline_multibuffer_empty_block_01.dump b/src/testdir/dumps/Test_diff_inline_multibuffer_empty_block_01.dump
new file mode 100644 (file)
index 0000000..fad9aac
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_inline_multibuffer_empty_block_01.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0|n|c|h|o|r|1| @10||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0|n|c|h|o|r|1| @7||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0|n|c|h|o|r|1| @8||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0|n|c|h|o|r|1| @7
+| +0#0000e05#a8a8a8255@1|1+0#0000000#ffd7ff255|2+2&#ff404010|3|4|5|6|7|8|9|0+0&#ffd7ff255|a|b|c|d+2&#ff404010|e| +0&#ffd7ff255@2||+1&#ffffff0| +0#0000e05#a8a8a8255@1|1+0#0000000#ffd7ff255|2+2&#ff404010|3|4|5|6|7|-@1|0+0&#ffd7ff255|a|b|c|-+2&#ff404010|e||+1&#ffffff0| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@15||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|1+0#0000000#ffd7ff255|?+2&#ff404010@6|9|0+0&#ffd7ff255|a|b|c|d+2&#ff404010|?
+| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0|n|c|h|o|r|2| @10||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0|n|c|h|o|r|2| @7||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0|n|c|h|o|r|2| @8||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0|n|c|h|o|r|2| @7
+|~+0#4040ff13&| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|~| @18||+1#0000000&|~+0#4040ff13&| @15||+1#0000000&|~+0#4040ff13&| @16||+1#0000000&|~+0#4040ff13&| @15
+|X+3#0000000&|d|i|f|i|l|e|1| @1|1|,|1| @3|A|l@1| |<+1&&|d|i|f|i|l|e|2| |1|,|1| @1|A|l@1| |<|d|i|f|i|l|e|3| |1|,|1| @2|A|l@1| |<|d|i|f|i|l|e|4| |1|,|1| @1|A|l@1
+|:+0&&> @73

diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index dc5dcc9a5e60a611b5b7617b092327d716c777e5..eee23729a1fd77ae7f3bca1523628bb552de1ae3 100644 (file)
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -2636,6 +2636,22 @@ func Test_diff_inline_multibuffer()
   call StopVimInTerminal(buf)
 endfunc
 
+" Test that when using multi-buffer diff, an empty block would be correctly
+" skipped in the result, without resulting in invalid states or crashes.
+func Test_diff_inline_multibuffer_empty_block()
+  CheckScreendump
+
+  call writefile(['anchor1', '1234567890abcde', 'anchor2'], 'Xdifile1')
+  call writefile(['anchor1', '1234567--0abc-e', 'anchor2'], 'Xdifile2')
+  call writefile(['anchor1', 'anchor2'], 'Xdifile3')
+  call writefile(['anchor1', '1???????90abcd?', 'anchor2'], 'Xdifile4')
+
+  let buf = RunVimInTerminal('-d Xdifile1 Xdifile2 Xdifile3 Xdifile4', {})
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_empty_block_01", " diffopt+=inline:char")
+
+  call StopVimInTerminal(buf)
+endfunc
+
 func Test_diffget_diffput_linematch()
   CheckScreendump
   call delete('.Xdifile1.swp')

diff --git a/src/version.c b/src/version.c
index a908f1179a02572d72877db5687f3bb39f64ef10..3b3f8ac979b68f1925c3f447d6a72dc684d5368c 100644 (file)
--- a/src/version.c
+++ b/src/version.c
@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1567,
 /**/
     1566,
 /**/