From: Hirohito Higashi Date: Sat, 20 Jun 2026 16:06:58 +0000 (+0000) Subject: patch 9.2.0679: [security]: Out-of-bounds read with text property virtual text X-Git-Tag: v9.2.0679^0 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=b3faeecc976d3031d7c0675623516ec60c30f949;p=thirdparty%2Fvim.git patch 9.2.0679: [security]: Out-of-bounds read with text property virtual text Problem: [security]: Out-of-bounds read with text property virtual text. A crafted undo file can declare a virtual-text property whose offset points outside the line's property data, so reading the virtual text reads out of bounds. This completes the count-only check added in 9.2.0670. Solution: Validate the virtual-text offset and length of each property against the available property data before turning the offset into a pointer. Github Security Advisory: https://github.com/vim/vim/security/advisories/GHSA-ww8h-47xp-hp4w Co-Authored-By: Claude Opus 4.8 (1M context) Signed-off-by: Hirohito Higashi Signed-off-by: Christian Brabandt --- diff --git a/src/proto/textprop.pro b/src/proto/textprop.pro index 82f47275f2..511d3b5065 100644 --- a/src/proto/textprop.pro +++ b/src/proto/textprop.pro @@ -37,4 +37,5 @@ int adjust_prop_columns(linenr_T lnum, colnr_T col, int bytes_added, int flags); void adjust_props_for_split(linenr_T lnum_props, linenr_T lnum_top, int kept, int deleted, int at_eol); void prepend_joined_props(unpacked_memline_T *um, linenr_T lnum, int last_line, long col, int removed); bool text_prop_count_valid(int prop_count, size_t propdata_len); +bool text_prop_vtext_valid(char_u *props, int prop_count, size_t propdata_len); /* vim: set ft=c : */ diff --git a/src/testdir/test_textprop2.vim b/src/testdir/test_textprop2.vim index fdebf794af..523a59b1b2 100644 --- a/src/testdir/test_textprop2.vim +++ b/src/testdir/test_textprop2.vim @@ -428,14 +428,12 @@ func Test_multiline_prop_delete_penultimate_line() call s:CleanupPropTypes(['1', '2', '3']) endfunc -func s:ManipulateUndoBlob(name) - " Patch the saved old line in the undo file: - " 00 00 00 08 'QQQQQQQQ' -> 00 00 00 27 'AAAA' NUL count=0xFFFF <32x00> - " i.e. textlen 8 text-only -> 39-byte blob: text "AAAA", NUL, prop_count - " 0xFFFF, one zeroed textprop_T(32). propdata_len becomes 34, count 65535. +func s:ManipulateUndoBlob(name, repl) + " Replace the saved old line (00 00 00 08 'QQQQQQQQ') in the undo file with + " the crafted "repl" blob, then read it back in. let blob = readfile(a:name, 'B') let marker = 0z000000085151515151515151 - let repl = 0z000000274141414100FFFF + repeat(0z00, 32) + let repl = a:repl let mlen = len(marker) let idx = -1 let i = 0 @@ -466,7 +464,10 @@ func Test_textprop_undo_bad_prop_count() let &ul = &ul call setline(1, 'BBBB') " undo step saves old line 1 = "QQQQQQQQ" wundo Xtpundo - call s:ManipulateUndoBlob('Xtpundo') + " 39-byte blob: "AAAA" NUL count=0xFFFF, one zeroed textprop_T(32). + " propdata_len becomes 34 while the count claims 65535 properties. + call s:ManipulateUndoBlob('Xtpundo', 0z000000274141414100FFFF + \ + repeat(0z00, 32)) undo @@ -488,4 +489,49 @@ func Test_textprop_undo_bad_prop_count() call delete('Xtpundo') endfunc +" A crafted undo file can restore a line whose virtual-text property declares an +" out-of-range tp_text_offset. Turning that offset into a pointer and reading +" the virtual text would read past the line buffer. Restore such a line and +" force a consumer; reaching the asserts (no ASan abort / crash) means the +" offset is bounded. +func Test_textprop_undo_bad_vtext_offset() + CheckFeature persistent_undo + + new + call setline(1, ['QQQQQQQQ', 'DECOYLINE']) + let &ul = &ul + call setline(1, 'BBBB') " undo step saves old line 1 = "QQQQQQQQ" + wundo Xtpundo + + " One textprop_T for a virtual text prop (tp_id < 0) whose tp_text_offset + " (0x00100000) points far past the 34-byte property data. The count (1) is + " valid, so only the offset/length check can reject this. + let prop = 0z01000000 " tp_col = 1 + let prop += 0z04000000 " tp_len = 4 + let prop += 0zFFFFFFFF " tp_id = -1 (virtual text) + let prop += 0z00000000 " tp_type = 0 + let prop += 0z00000000 " tp_flags = 0 + let prop += 0z00000000 " tp_padleft = 0 + let prop += 0z00001000 " u.tp_text_offset = 0x00100000 + let prop += 0z00000000 " union upper bytes + call s:ManipulateUndoBlob('Xtpundo', 0z000000274141414100 + 0z0100 + prop) + + undo + + " Safety: prove the malicious line was actually restored before the consumer + " runs, so the test can't pass vacuously if the patch missed. + call assert_equal('AAAA', getline(1)) + + call prop_type_add('Xtp', {}) + call prop_add(2, 1, {'type': 'Xtp', 'length': 1}) + + " this caused OOB read, now it is rejected as a corrupted (untrusted) undo + " file with a catchable error + call assert_fails('call prop_list(1)', 'E967:') + + call prop_type_delete('Xtp') + bwipe! + call delete('Xtpundo') +endfunc + " vim: shiftwidth=2 sts=2 expandtab diff --git a/src/textprop.c b/src/textprop.c index e13e44b946..6d5a108631 100644 --- a/src/textprop.c +++ b/src/textprop.c @@ -118,6 +118,13 @@ um_goto_line(unpacked_memline_T *um, linenr_T lnum, int extra_props) proplen = (int)prop_count; props_start = count_ptr + PROP_COUNT_SIZE; + if (!text_prop_vtext_valid(props_start, proplen, propdata_len)) + { + emsg(e_text_property_info_corrupted); + um->buf = NULL; + return false; + } + um->props = ALLOC_MULT(textprop_T, proplen + extra_props); if (um->props == NULL) { @@ -1246,6 +1253,12 @@ get_text_props(buf_T *buf, linenr_T lnum, char_u **props, int will_change) emsg(e_text_property_info_corrupted); return 0; } + if (!text_prop_vtext_valid(text + textlen + PROP_COUNT_SIZE, + (int)prop_count, propdata_len)) + { + emsg(e_text_property_info_corrupted); + return 0; + } *props = text + textlen + PROP_COUNT_SIZE; return (int)prop_count; } @@ -3268,4 +3281,27 @@ text_prop_count_valid(int prop_count, size_t propdata_len) <= propdata_len - PROP_COUNT_SIZE; } +/* + * Return true when every virtual text property's offset and length stay within + * "propdata_len", so tp_text_offset can be safely turned into a pointer. + * "props" may be unaligned. + */ + bool +text_prop_vtext_valid(char_u *props, int prop_count, size_t propdata_len) +{ + for (int i = 0; i < prop_count; ++i) + { + textprop_T prop; + + mch_memmove(&prop, props + (size_t)i * sizeof(textprop_T), + sizeof(textprop_T)); + if (prop.tp_id >= 0 || prop.u.tp_text_offset <= 0) + continue; + if (prop.tp_len < 0 || (size_t)prop.u.tp_text_offset + + (size_t)prop.tp_len + 1 > propdata_len) + return false; + } + return true; +} + #endif // FEAT_PROP_POPUP diff --git a/src/version.c b/src/version.c index 9de098d718..933e847377 100644 --- a/src/version.c +++ b/src/version.c @@ -759,6 +759,8 @@ static char *(features[]) = static int included_patches[] = { /* Add new patch number below this line */ +/**/ + 679, /**/ 678, /**/