98694166c2
An interrupt handler shall not be called from another interrupt
handler otherwise this leads to problems like the following:
Kernel attempted to write user page (afd4fa84) - exploit attempt? (uid: 1000)
------------[ cut here ]------------
Bug: Write fault blocked by KUAP!
WARNING: CPU: 0 PID: 1617 at arch/powerpc/mm/fault.c:230 do_page_fault+0x484/0x720
Modules linked in:
CPU: 0 PID: 1617 Comm: sshd Tainted: G W 5.13.0-pmac-00010-g8393422eb77 #7
NIP: c001b77c LR: c001b77c CTR: 00000000
REGS: cb9e5bc0 TRAP: 0700 Tainted: G W (5.13.0-pmac-00010-g8393422eb77)
MSR: 00021032 <ME,IR,DR,RI> CR: 24942424 XER: 00000000
GPR00: c001b77c cb9e5c80 c1582c00 00000021 3ffffbff 085b0000 00000027 c8eb644c
GPR08: 00000023 00000000 00000000 00000000 24942424 0063f8c8 00000000 000186a0
GPR16: afd52dd4 afd52dd0 afd52dcc afd52dc8 0065a990 c07640c4 cb9e5e98 cb9e5e90
GPR24: 00000040 afd4fa96 00000040 02000000 c1fda6c0 afd4fa84 00000300 cb9e5cc0
NIP [c001b77c] do_page_fault+0x484/0x720
LR [c001b77c] do_page_fault+0x484/0x720
Call Trace:
[cb9e5c80] [c001b77c] do_page_fault+0x484/0x720 (unreliable)
[cb9e5cb0] [c000424c] DataAccess_virt+0xd4/0xe4
--- interrupt: 300 at __copy_tofrom_user+0x110/0x20c
NIP: c001f9b4 LR: c03250a0 CTR: 00000004
REGS: cb9e5cc0 TRAP: 0300 Tainted: G W (5.13.0-pmac-00010-g8393422eb77)
MSR: 00009032 <EE,ME,IR,DR,RI> CR: 48028468 XER: 20000000
DAR: afd4fa84 DSISR: 0a000000
GPR00: 20726f6f cb9e5d80 c1582c00 00000004 cb9e5e3a 00000016 afd4fa80 00000000
GPR08: 3835202d 72777872 2d78722d 00000004 28028464 0063f8c8 00000000 000186a0
GPR16: afd52dd4 afd52dd0 afd52dcc afd52dc8 0065a990 c07640c4 cb9e5e98 cb9e5e90
GPR24: 00000040 afd4fa96 00000040 cb9e5e0c 00000daa a0000000 cb9e5e98 afd4fa56
NIP [c001f9b4] __copy_tofrom_user+0x110/0x20c
LR [c03250a0] _copy_to_iter+0x144/0x990
--- interrupt: 300
[cb9e5d80] [c03e89c0] n_tty_read+0xa4/0x598 (unreliable)
[cb9e5df0] [c03e2a0c] tty_read+0xdc/0x2b4
[cb9e5e80] [c0156bf8] vfs_read+0x274/0x340
[cb9e5f00] [c01571ac] ksys_read+0x70/0x118
[cb9e5f30] [c0016048] ret_from_syscall+0x0/0x28
--- interrupt: c00 at 0xa7855c88
NIP: a7855c88 LR: a7855c5c CTR: 00000000
REGS: cb9e5f40 TRAP: 0c00 Tainted: G W (5.13.0-pmac-00010-g8393422eb77)
MSR: 0000d032 <EE,PR,ME,IR,DR,RI> CR: 2402446c XER: 00000000
GPR00: 00000003 afd4ec70 a72137d0 0000000b afd4ecac 00004000 0065a990 00000800
GPR08: 00000000 a7947930 00000000 00000004 c15831b0 0063f8c8 00000000 000186a0
GPR16: afd52dd4 afd52dd0 afd52dcc afd52dc8 0065a990 0065a9e0 00000001 0065fac0
GPR24: 00000000 00000089 00664050 00000000 00668e30 a720c8dc a7943ff4 0065f9b0
NIP [a7855c88] 0xa7855c88
LR [a7855c5c] 0xa7855c5c
--- interrupt: c00
Instruction dump:
3884aa88 38630178 48076861 807f0080 48042e45 2f830000 419e0148 3c80c079
3c60c076 38841be4 386301c0 4801f705 <0fe00000> 3860000b 4bfffe30 3c80c06b
---[ end trace fd69b91a8046c2e5 ]---
Here the problem is that by re-enterring an exception handler,
kuap_save_and_lock() is called a second time with this time KUAP
access locked, leading to regs->kuap being overwritten hence
KUAP not being unlocked at exception exit as expected.
Do not call do_IRQ() from timer_interrupt() directly. Instead,
redefine do_IRQ() as a standard function named __do_IRQ(), and
call it from both do_IRQ() and time_interrupt() handlers.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.