kernel/linux.git/lib/test_user_copy.c, branch v6.6.132

usercopy: Avoid soft lockups in test_check_nonzero_user()

2019-10-16T12:56:21+00:00

On a machine with a 64K PAGE_SIZE, the nested for loops in test_check_nonzero_user() can lead to soft lockups, eg: watchdog: BUG: soft lockup - CPU#4 stuck for 22s! [modprobe:611] Modules linked in: test_user_copy(+) vmx_crypto gf128mul crc32c_vpmsum virtio_balloon ip_tables x_tables autofs4 CPU: 4 PID: 611 Comm: modprobe Tainted: G L 5.4.0-rc1-gcc-8.2.0-00001-gf5a1a536fa14-dirty #1151 ... NIP __might_sleep+0x20/0xc0 LR __might_fault+0x40/0x60 Call Trace: check_zeroed_user+0x12c/0x200 test_user_copy_init+0x67c/0x1210 [test_user_copy] do_one_initcall+0x60/0x340 do_init_module+0x7c/0x2f0 load_module+0x2d94/0x30e0 __do_sys_finit_module+0xc8/0x150 system_call+0x5c/0x68 Even with a 4K PAGE_SIZE the test takes multiple seconds. Instead tweak it to only scan a 1024 byte region, but make it cross the page boundary. Fixes: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Suggested-by: Aleksa Sarai Signed-off-by: Michael Ellerman Reviewed-by: Aleksa Sarai Acked-by: Christian Brauner Link: https://lore.kernel.org/r/20191016122732.13467-1-mpe@ellerman.id.au Signed-off-by: Christian Brauner

lib: test_user_copy: style cleanup

2019-10-07T00:03:07+00:00

While writing the tests for copy_struct_from_user(), I used a construct that Linus doesn't appear to be too fond of: On 2019-10-04, Linus Torvalds wrote: > Hmm. That code is ugly, both before and after the fix. > > This just doesn't make sense for so many reasons: > > if ((ret |= test(umem_src == NULL, "kmalloc failed"))) > > where the insanity comes from > > - why "|=" when you know that "ret" was zero before (and it had to > be, for the test to make sense) > > - why do this as a single line anyway? > > - don't do the stupid "double parenthesis" to hide a warning. Make it > use an actual comparison if you add a layer of parentheses. So instead, use a bog-standard check that isn't nearly as ugly. Fixes: 341115822f88 ("usercopy: Add parentheses around assignment in test_copy_struct_from_user") Fixes: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Signed-off-by: Aleksa Sarai Reviewed-by: Nathan Chancellor Reviewed-by: Christian Brauner Link: https://lore.kernel.org/r/20191005233028.18566-1-cyphar@cyphar.com Signed-off-by: Christian Brauner

usercopy: Add parentheses around assignment in test_copy_struct_from_user

2019-10-03T19:13:27+00:00

Clang warns: lib/test_user_copy.c:96:10: warning: using the result of an assignment as a condition without parentheses [-Wparentheses] if (ret |= test(umem_src == NULL, "kmalloc failed")) ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ lib/test_user_copy.c:96:10: note: place parentheses around the assignment to silence this warning if (ret |= test(umem_src == NULL, "kmalloc failed")) ^ ( ) lib/test_user_copy.c:96:10: note: use '!=' to turn this compound assignment into an inequality comparison if (ret |= test(umem_src == NULL, "kmalloc failed")) ^~ != Add the parentheses as it suggests because this is intentional. Fixes: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Link: https://github.com/ClangBuiltLinux/linux/issues/731 Signed-off-by: Nathan Chancellor Acked-by: Aleksa Sarai Acked-by: Christian Brauner Link: https://lore.kernel.org/r/20191003171121.2723619-1-natechancellor@gmail.com Signed-off-by: Christian Brauner

lib: introduce copy_struct_from_user() helper

2019-10-01T13:45:03+00:00

A common pattern for syscall extensions is increasing the size of a struct passed from userspace, such that the zero-value of the new fields result in the old kernel behaviour (allowing for a mix of userspace and kernel vintages to operate on one another in most cases). While this interface exists for communication in both directions, only one interface is straightforward to have reasonable semantics for (userspace passing a struct to the kernel). For kernel returns to userspace, what the correct semantics are (whether there should be an error if userspace is unaware of a new extension) is very syscall-dependent and thus probably cannot be unified between syscalls (a good example of this problem is [1]). Previously there was no common lib/ function that implemented the necessary extension-checking semantics (and different syscalls implemented them slightly differently or incompletely[2]). Future patches replace common uses of this pattern to make use of copy_struct_from_user(). Some in-kernel selftests that insure that the handling of alignment and various byte patterns are all handled identically to memchr_inv() usage. [1]: commit 1251201c0d34 ("sched/core: Fix uclamp ABI bug, clean up and robustify sched_read_attr() ABI logic and code") [2]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do similar checks to copy_struct_from_user() while rt_sigprocmask(2) always rejects differently-sized struct arguments. Suggested-by: Rasmus Villemoes Signed-off-by: Aleksa Sarai Reviewed-by: Kees Cook Reviewed-by: Christian Brauner Link: https://lore.kernel.org/r/20191001011055.19283-2-cyphar@cyphar.com Signed-off-by: Christian Brauner

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282

2019-06-05T15:36:37+00:00

Based on 1 normalized pattern(s): this software is licensed under the terms of the gnu general public license version 2 as published by the free software foundation and may be copied distributed and modified under those terms this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 285 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Alexios Zavras Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141900.642774971@linutronix.de Signed-off-by: Greg Kroah-Hartman

treewide: simplify Kconfig dependencies for removed archs

2018-03-26T13:55:57+00:00

A lot of Kconfig symbols have architecture specific dependencies. In those cases that depend on architectures we have already removed, they can be omitted. Acked-by: Kalle Valo Acked-by: Alexandre Belloni Signed-off-by: Arnd Bergmann

mn10300: Remove the architecture

2018-03-09T22:19:56+00:00

Remove the MN10300 arch as the hardware is defunct. Suggested-by: Arnd Bergmann Signed-off-by: David Howells cc: Masahiro Yamada cc: linux-am33-list@redhat.com Signed-off-by: Arnd Bergmann

lib: remove check for AVR32 arch in test_user_copy

2017-05-01T07:36:30+00:00

The AVR32 architecture support has been removed from the Linux kernel, hence remove all the check for this architecture in test_user_copy.c. Signed-off-by: Hans-Christian Noren Egtvedt

usercopy: ARM NOMMU has no 64-bit get_user

2017-02-22T19:24:08+00:00

On a NOMMU ARM kernel, we get this link error: ERROR: "__get_user_bad" [lib/test_user_copy.ko] undefined! The problem is that the extended get_user/put_user definitions were only added for the normal (MMU based) case. We could add it for NOMMU as well, but it seems easier to just not call it, since no other code needs it. Fixes: 4c5d7bc63775 ("usercopy: Add tests for all get_user() sizes") Signed-off-by: Arnd Bergmann Signed-off-by: Kees Cook

usercopy: Add tests for all get_user() sizes

2017-02-21T19:59:38+00:00

The existing test was only exercising native unsigned long size get_user(). For completeness, we should check all sizes. But we must skip some 32-bit architectures that don't implement a 64-bit get_user(). These new tests actually uncovered a bug in ARM's 64-bit get_user() zeroing. Signed-off-by: Kees Cook