commit-graph: bounds-check generation overflow chunk

If the generation entry in a commit-graph doesn't fit, we instead insert
an offset into a generation overflow chunk. But since we don't record
the size of the chunk, we may read outside the chunk if the offset we
find on disk is malicious or corrupted.

We can't check the size of the chunk up-front; it will vary based on how
many entries need overflow. So instead, we'll do a bounds-check before
accessing the chunk memory. Unfortunately there is no error-return from
this function, so we'll just have to die(), which is what it does for
other forms of corruption.

As with other cases, we can drop the st_mult() call, since we know our
bounds-checked value will fit within a size_t.

Before this patch, the test here actually "works" because we read
garbage data from the next chunk. And since that garbage data happens
not to provide a generation number which changes the output, it appears
to work. We could construct a case that actually segfaults or produces
wrong output, but it would be a bit tricky. For our purposes its
sufficient to check that we've detected the bounds error.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
3 files changed
tree: d8833327e28205cad1b3748d9776c2597f47dd2d
  1. .github/
  2. block-sha1/
  3. builtin/
  4. ci/
  5. compat/
  6. contrib/
  7. Documentation/
  8. ewah/
  9. git-gui/
  10. gitk-git/
  11. gitweb/
  12. mergetools/
  13. negotiator/
  14. oss-fuzz/
  15. perl/
  16. po/
  17. refs/
  18. reftable/
  19. sha1/
  20. sha1dc/
  21. sha256/
  22. t/
  23. templates/
  24. trace2/
  25. xdiff/
  26. .cirrus.yml
  27. .clang-format
  28. .editorconfig
  29. .gitattributes
  30. .gitignore
  31. .gitmodules
  32. .mailmap
  33. .tsan-suppressions
  34. abspath.c
  35. abspath.h
  36. aclocal.m4
  37. add-interactive.c
  38. add-interactive.h
  39. add-patch.c
  40. advice.c
  41. advice.h
  42. alias.c
  43. alias.h
  44. alloc.c
  45. alloc.h
  46. apply.c
  47. apply.h
  48. archive-tar.c
  49. archive-zip.c
  50. archive.c
  51. archive.h
  52. attr.c
  53. attr.h
  54. banned.h
  55. base85.c
  56. base85.h
  57. bisect.c
  58. bisect.h
  59. blame.c
  60. blame.h
  61. blob.c
  62. blob.h
  63. bloom.c
  64. bloom.h
  65. branch.c
  66. branch.h
  67. builtin.h
  68. bulk-checkin.c
  69. bulk-checkin.h
  70. bundle-uri.c
  71. bundle-uri.h
  72. bundle.c
  73. bundle.h
  74. cache-tree.c
  75. cache-tree.h
  76. cbtree.c
  77. cbtree.h
  78. chdir-notify.c
  79. chdir-notify.h
  80. check-builtins.sh
  81. checkout.c
  82. checkout.h
  83. chunk-format.c
  84. chunk-format.h
  85. CODE_OF_CONDUCT.md
  86. color.c
  87. color.h
  88. column.c
  89. column.h
  90. combine-diff.c
  91. command-list.txt
  92. commit-graph.c
  93. commit-graph.h
  94. commit-reach.c
  95. commit-reach.h
  96. commit-slab-decl.h
  97. commit-slab-impl.h
  98. commit-slab.h
  99. commit.c
  100. commit.h
  101. common-main.c
  102. config.c
  103. config.h
  104. config.mak.dev
  105. config.mak.in
  106. config.mak.uname
  107. configure.ac
  108. connect.c
  109. connect.h
  110. connected.c
  111. connected.h
  112. convert.c
  113. convert.h
  114. copy.c
  115. copy.h
  116. COPYING
  117. credential.c
  118. credential.h
  119. csum-file.c
  120. csum-file.h
  121. ctype.c
  122. daemon.c
  123. date.c
  124. date.h
  125. decorate.c
  126. decorate.h
  127. delta-islands.c
  128. delta-islands.h
  129. delta.h
  130. detect-compiler
  131. diagnose.c
  132. diagnose.h
  133. diff-delta.c
  134. diff-lib.c
  135. diff-merges.c
  136. diff-merges.h
  137. diff-no-index.c
  138. diff.c
  139. diff.h
  140. diffcore-break.c
  141. diffcore-delta.c
  142. diffcore-order.c
  143. diffcore-pickaxe.c
  144. diffcore-rename.c
  145. diffcore-rotate.c
  146. diffcore.h
  147. dir-iterator.c
  148. dir-iterator.h
  149. dir.c
  150. dir.h
  151. editor.c
  152. editor.h
  153. entry.c
  154. entry.h
  155. environment.c
  156. environment.h
  157. exec-cmd.c
  158. exec-cmd.h
  159. fetch-negotiator.c
  160. fetch-negotiator.h
  161. fetch-pack.c
  162. fetch-pack.h
  163. fmt-merge-msg.c
  164. fmt-merge-msg.h
  165. fsck.c
  166. fsck.h
  167. fsmonitor--daemon.h
  168. fsmonitor-ipc.c
  169. fsmonitor-ipc.h
  170. fsmonitor-ll.h
  171. fsmonitor-path-utils.h
  172. fsmonitor-settings.c
  173. fsmonitor-settings.h
  174. fsmonitor.c
  175. fsmonitor.h
  176. generate-cmdlist.sh
  177. generate-configlist.sh
  178. generate-hooklist.sh
  179. gettext.c
  180. gettext.h
  181. git-archimport.perl
  182. git-compat-util.h
  183. git-curl-compat.h
  184. git-cvsexportcommit.perl
  185. git-cvsimport.perl
  186. git-cvsserver.perl
  187. git-difftool--helper.sh
  188. git-filter-branch.sh
  189. git-instaweb.sh
  190. git-merge-octopus.sh
  191. git-merge-one-file.sh
  192. git-merge-resolve.sh
  193. git-mergetool--lib.sh
  194. git-mergetool.sh
  195. git-p4.py
  196. git-quiltimport.sh
  197. git-request-pull.sh
  198. git-send-email.perl
  199. git-sh-i18n.sh
  200. git-sh-setup.sh
  201. git-submodule.sh
  202. git-svn.perl
  203. GIT-VERSION-GEN
  204. git-web--browse.sh
  205. git-zlib.c
  206. git-zlib.h
  207. git.c
  208. git.rc
  209. gpg-interface.c
  210. gpg-interface.h
  211. graph.c
  212. graph.h
  213. grep.c
  214. grep.h
  215. hash-ll.h
  216. hash-lookup.c
  217. hash-lookup.h
  218. hash.h
  219. hashmap.c
  220. hashmap.h
  221. help.c
  222. help.h
  223. hex.c
  224. hex.h
  225. hook.c
  226. hook.h
  227. http-backend.c
  228. http-fetch.c
  229. http-push.c
  230. http-walker.c
  231. http.c
  232. http.h
  233. ident.c
  234. ident.h
  235. imap-send.c
  236. INSTALL
  237. iterator.h
  238. json-writer.c
  239. json-writer.h
  240. khash.h
  241. kwset.c
  242. kwset.h
  243. levenshtein.c
  244. levenshtein.h
  245. LGPL-2.1
  246. line-log.c
  247. line-log.h
  248. line-range.c
  249. line-range.h
  250. linear-assignment.c
  251. linear-assignment.h
  252. list-objects-filter-options.c
  253. list-objects-filter-options.h
  254. list-objects-filter.c
  255. list-objects-filter.h
  256. list-objects.c
  257. list-objects.h
  258. list.h
  259. lockfile.c
  260. lockfile.h
  261. log-tree.c
  262. log-tree.h
  263. ls-refs.c
  264. ls-refs.h
  265. mailinfo.c
  266. mailinfo.h
  267. mailmap.c
  268. mailmap.h
  269. Makefile
  270. match-trees.c
  271. match-trees.h
  272. mem-pool.c
  273. mem-pool.h
  274. merge-blobs.c
  275. merge-blobs.h
  276. merge-ll.c
  277. merge-ll.h
  278. merge-ort-wrappers.c
  279. merge-ort-wrappers.h
  280. merge-ort.c
  281. merge-ort.h
  282. merge-recursive.c
  283. merge-recursive.h
  284. merge.c
  285. merge.h
  286. mergesort.h
  287. midx.c
  288. midx.h
  289. name-hash.c
  290. name-hash.h
  291. notes-cache.c
  292. notes-cache.h
  293. notes-merge.c
  294. notes-merge.h
  295. notes-utils.c
  296. notes-utils.h
  297. notes.c
  298. notes.h
  299. object-file.c
  300. object-file.h
  301. object-name.c
  302. object-name.h
  303. object-store-ll.h
  304. object-store.h
  305. object.c
  306. object.h
  307. oid-array.c
  308. oid-array.h
  309. oidmap.c
  310. oidmap.h
  311. oidset.c
  312. oidset.h
  313. oidtree.c
  314. oidtree.h
  315. pack-bitmap-write.c
  316. pack-bitmap.c
  317. pack-bitmap.h
  318. pack-check.c
  319. pack-mtimes.c
  320. pack-mtimes.h
  321. pack-objects.c
  322. pack-objects.h
  323. pack-revindex.c
  324. pack-revindex.h
  325. pack-write.c
  326. pack.h
  327. packfile.c
  328. packfile.h
  329. pager.c
  330. pager.h
  331. parallel-checkout.c
  332. parallel-checkout.h
  333. parse-options-cb.c
  334. parse-options.c
  335. parse-options.h
  336. patch-delta.c
  337. patch-ids.c
  338. patch-ids.h
  339. path.c
  340. path.h
  341. pathspec.c
  342. pathspec.h
  343. pkt-line.c
  344. pkt-line.h
  345. preload-index.c
  346. preload-index.h
  347. pretty.c
  348. pretty.h
  349. prio-queue.c
  350. prio-queue.h
  351. progress.c
  352. progress.h
  353. promisor-remote.c
  354. promisor-remote.h
  355. prompt.c
  356. prompt.h
  357. protocol-caps.c
  358. protocol-caps.h
  359. protocol.c
  360. protocol.h
  361. prune-packed.c
  362. prune-packed.h
  363. quote.c
  364. quote.h
  365. range-diff.c
  366. range-diff.h
  367. reachable.c
  368. reachable.h
  369. read-cache-ll.h
  370. read-cache.c
  371. read-cache.h
  372. README.md
  373. rebase-interactive.c
  374. rebase-interactive.h
  375. rebase.c
  376. rebase.h
  377. ref-filter.c
  378. ref-filter.h
  379. reflog-walk.c
  380. reflog-walk.h
  381. reflog.c
  382. reflog.h
  383. refs.c
  384. refs.h
  385. refspec.c
  386. refspec.h
  387. remote-curl.c
  388. remote.c
  389. remote.h
  390. replace-object.c
  391. replace-object.h
  392. repo-settings.c
  393. repository.c
  394. repository.h
  395. rerere.c
  396. rerere.h
  397. reset.c
  398. reset.h
  399. resolve-undo.c
  400. resolve-undo.h
  401. revision.c
  402. revision.h
  403. run-command.c
  404. run-command.h
  405. sane-ctype.h
  406. scalar.c
  407. SECURITY.md
  408. send-pack.c
  409. send-pack.h
  410. sequencer.c
  411. sequencer.h
  412. serve.c
  413. serve.h
  414. server-info.c
  415. server-info.h
  416. setup.c
  417. setup.h
  418. sh-i18n--envsubst.c
  419. sha1dc_git.c
  420. sha1dc_git.h
  421. shallow.c
  422. shallow.h
  423. shared.mak
  424. shell.c
  425. shortlog.h
  426. sideband.c
  427. sideband.h
  428. sigchain.c
  429. sigchain.h
  430. simple-ipc.h
  431. sparse-index.c
  432. sparse-index.h
  433. split-index.c
  434. split-index.h
  435. stable-qsort.c
  436. statinfo.c
  437. statinfo.h
  438. strbuf.c
  439. strbuf.h
  440. streaming.c
  441. streaming.h
  442. string-list.c
  443. string-list.h
  444. strmap.c
  445. strmap.h
  446. strvec.c
  447. strvec.h
  448. sub-process.c
  449. sub-process.h
  450. submodule-config.c
  451. submodule-config.h
  452. submodule.c
  453. submodule.h
  454. symlinks.c
  455. symlinks.h
  456. tag.c
  457. tag.h
  458. tar.h
  459. tempfile.c
  460. tempfile.h
  461. thread-utils.c
  462. thread-utils.h
  463. tmp-objdir.c
  464. tmp-objdir.h
  465. trace.c
  466. trace.h
  467. trace2.c
  468. trace2.h
  469. trailer.c
  470. trailer.h
  471. transport-helper.c
  472. transport-internal.h
  473. transport.c
  474. transport.h
  475. tree-diff.c
  476. tree-walk.c
  477. tree-walk.h
  478. tree.c
  479. tree.h
  480. unicode-width.h
  481. unimplemented.sh
  482. unix-socket.c
  483. unix-socket.h
  484. unix-stream-server.c
  485. unix-stream-server.h
  486. unpack-trees.c
  487. unpack-trees.h
  488. upload-pack.c
  489. upload-pack.h
  490. url.c
  491. url.h
  492. urlmatch.c
  493. urlmatch.h
  494. usage.c
  495. userdiff.c
  496. userdiff.h
  497. utf8.c
  498. utf8.h
  499. varint.c
  500. varint.h
  501. version.c
  502. version.h
  503. versioncmp.c
  504. versioncmp.h
  505. walker.c
  506. walker.h
  507. wildmatch.c
  508. wildmatch.h
  509. worktree.c
  510. worktree.h
  511. wrap-for-bin.sh
  512. wrapper.c
  513. wrapper.h
  514. write-or-die.c
  515. write-or-die.h
  516. ws.c
  517. ws.h
  518. wt-status.c
  519. wt-status.h
  520. xdiff-interface.c
  521. xdiff-interface.h
README.md

Build status

Git - fast, scalable, distributed revision control system

Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.

Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.

Please read the file INSTALL for installation instructions.

Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.

See Documentation/gittutorial.txt to get started, then see Documentation/giteveryday.txt for a useful minimum set of commands, and Documentation/git-<commandname>.txt for documentation of each command. If git has been correctly installed, then the tutorial can also be read with man gittutorial or git help tutorial, and the documentation of each command with man git-<commandname> or git help <commandname>.

CVS users may also want to read Documentation/gitcvs-migration.txt (man gitcvs-migration or git help cvs-migration if git is installed).

The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).

Those wishing to help with error message, usage and informational message string translations (localization l10) should see po/README.md (a po file is a Portable Object file that holds the translations).

To subscribe to the list, send an email with just “subscribe git” in the body to majordomo@vger.kernel.org (not the Git list). The mailing list archives are available at https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.

Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.

The maintainer frequently sends the “What's cooking” reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.

The name “git” was given by Linus Torvalds when he wrote the very first version. He described the tool as “the stupid content tracker” and the name as (depending on your mood):

  • random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of “get” may or may not be relevant.
  • stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
  • “global information tracker”: you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
  • “goddamn idiotic truckload of sh*t”: when it breaks