|author||Joshua Peraza <firstname.lastname@example.org>||Tue Nov 06 21:19:06 2018|
|committer||Commit Bot <email@example.com>||Tue Nov 06 21:38:33 2018|
Reland "Use a relative address in .note.crashpad.info" This is a reland of 95e97a32eba4d505ab9591e683d2147c441eea48 Original change's description: > Use a relative address in .note.crashpad.info > > The desc value in the note is now the offset of CRASHPAD_INFO_SYMBOL > from desc. > > Making this note writable can trigger a linker error resulting in > the binary embedding .note.crashpad.info to be rejected by the > kernel during program loading. > > The error was observed with: > GNU ld (GNU Binutils for Debian) 2.30 > clang version 4.0.1-10 (tags/RELEASE_401/final) > Debian 4.17.17-1rodete2 > > When the note is made writable, crashpad_snapshot_test contains two > PT_LOAD segments which map to the same page. > > LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000 > 0x0000000000000258 0x0000000000000258 R 0x200000 > LOAD 0x0000000000000258 0x0000000000000258 0x0000000000000258 > 0x00000000002b84d8 0x00000000002b8950 RWE 0x200000 > > Executing this binary with the execv system call triggers a segfault > during program loading (an error can't be returned because the original > process vm has already been discarded). > > I suspect (I haven't set up a debuggable kernel) the failure occurs > while attempting to map the second load segment because its virtual > address, 0x258, is in the same page as the first load segment. > https://elixir.bootlin.com/linux/v4.17.17/source/fs/binfmt_elf.c#L380 > > The linker normally produces consecutive load segments where the second > segment is loaded 0x200000 bytes after the first, which I think is the > maximum expected page size. Modifying the test executable to load the > second segment at 0x1258 (4096 byte page size) allows program loading > to succeed (but of course crashes after control is given to it). > > Bug: crashpad:260 > Change-Id: I2b9f1e66e98919138baef3da991a9710bd970dc4 > Reviewed-on: https://chromium-review.googlesource.com/c/1292232 > Reviewed-by: Scott Graham <firstname.lastname@example.org> > Reviewed-by: Mark Mentovai <email@example.com> > Commit-Queue: Joshua Peraza <firstname.lastname@example.org> Bug: crashpad:260 Change-Id: I66713de84cc26c9119e0454d19c9c189263fe054 Reviewed-on: https://chromium-review.googlesource.com/c/1318066 Commit-Queue: Joshua Peraza <email@example.com> Reviewed-by: Mark Mentovai <firstname.lastname@example.org> Reviewed-by: Scott Graham <email@example.com>
Crashpad is a crash-reporting system.
Crashpad’s source code is hosted in a Git repository at https://chromium.googlesource.com/crashpad/crashpad.