kernel/linux.git/tools/testing/selftests/core, branch v5.10.257

fix bitmap corruption on close_range() with CLOSE_RANGE_UNSHARE

2024-09-04T11:17:30+00:00

commit 9a2fa1472083580b6c66bdaf291f591e1170123a upstream. copy_fd_bitmaps(new, old, count) is expected to copy the first count/BITS_PER_LONG bits from old->full_fds_bits[] and fill the rest with zeroes. What it does is copying enough words (BITS_TO_LONGS(count/BITS_PER_LONG)), then memsets the rest. That works fine, *if* all bits past the cutoff point are clear. Otherwise we are risking garbage from the last word we'd copied. For most of the callers that is true - expand_fdtable() has count equal to old->max_fds, so there's no open descriptors past count, let alone fully occupied words in ->open_fds[], which is what bits in ->full_fds_bits[] correspond to. The other caller (dup_fd()) passes sane_fdtable_size(old_fdt, max_fds), which is the smallest multiple of BITS_PER_LONG that covers all opened descriptors below max_fds. In the common case (copying on fork()) max_fds is ~0U, so all opened descriptors will be below it and we are fine, by the same reasons why the call in expand_fdtable() is safe. Unfortunately, there is a case where max_fds is less than that and where we might, indeed, end up with junk in ->full_fds_bits[] - close_range(from, to, CLOSE_RANGE_UNSHARE) with * descriptor table being currently shared * 'to' being above the current capacity of descriptor table * 'from' being just under some chunk of opened descriptors. In that case we end up with observably wrong behaviour - e.g. spawn a child with CLONE_FILES, get all descriptors in range 0..127 open, then close_range(64, ~0U, CLOSE_RANGE_UNSHARE) and watch dup(0) ending up with descriptor #128, despite #64 being observably not open. The minimally invasive fix would be to deal with that in dup_fd(). If this proves to add measurable overhead, we can go that way, but let's try to fix copy_fd_bitmaps() first. * new helper: bitmap_copy_and_expand(to, from, bits_to_copy, size). * make copy_fd_bitmaps() take the bitmap size in words, rather than bits; it's 'count' argument is always a multiple of BITS_PER_LONG, so we are not losing any information, and that way we can use the same helper for all three bitmaps - compiler will see that count is a multiple of BITS_PER_LONG for the large ones, so it'll generate plain memcpy()+memset(). Reproducer added to tools/testing/selftests/core/close_range_test.c Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

selftests/core: fix conflicting types compile error for close_range()

2021-11-18T13:04:01+00:00

[ Upstream commit f35dcaa0a8a29188ed61083d153df1454cf89d08 ] close_range() test type conflicts with close_range() library call in x86_64-linux-gnu/bits/unistd_ext.h. Fix it by changing the name to core_close_range(). gcc -g -I../../../../usr/include/ close_range_test.c -o ../tools/testing/selftests/core/close_range_test In file included from close_range_test.c:16: close_range_test.c:57:6: error: conflicting types for ‘close_range’; have ‘void(struct __test_metadata *)’ 57 | TEST(close_range) | ^~~~~~~~~~~ ../kselftest_harness.h:181:21: note: in definition of macro ‘__TEST_IMPL’ 181 | static void test_name(struct __test_metadata *_metadata); \ | ^~~~~~~~~ close_range_test.c:57:1: note: in expansion of macro ‘TEST’ 57 | TEST(close_range) | ^~~~ In file included from /usr/include/unistd.h:1204, from close_range_test.c:13: /usr/include/x86_64-linux-gnu/bits/unistd_ext.h:56:12: note: previous declaration of ‘close_range’ with type ‘int(unsigned int, unsigned int, int)’ 56 | extern int close_range (unsigned int __fd, unsigned int __max_fd, | ^~~~~~~~~~~ Signed-off-by: Shuah Khan Signed-off-by: Sasha Levin

selftests: core: use SKIP instead of XFAIL in close_range_test.c

2020-11-05T17:08:15+00:00

XFAIL is gone since commit 9847d24af95c ("selftests/harness: Refactor XFAIL into SKIP"), use SKIP instead. Fixes: 9847d24af95c ("selftests/harness: Refactor XFAIL into SKIP") Signed-off-by: Tommi Rantala Reviewed-by: Kees Cook Acked-by: Christian Brauner Signed-off-by: Shuah Khan

tests: add CLOSE_RANGE_UNSHARE tests

2020-06-16T22:07:38+00:00

Signed-off-by: Christian Brauner

tests: add close_range() tests

2020-06-16T22:07:38+00:00

This adds basic tests for the new close_range() syscall. - test that no invalid flags can be passed - test that a range of file descriptors is correctly closed - test that a range of file descriptors is correctly closed if there there are already closed file descriptors in the range - test that max_fd is correctly capped to the current fdtable maximum Signed-off-by: Christian Brauner Cc: Arnd Bergmann Cc: Jann Horn Cc: David Howells Cc: Dmitry V. Levin Cc: Oleg Nesterov Cc: Linus Torvalds Cc: Florian Weimer Cc: Shuah Khan Cc: linux-api@vger.kernel.org Cc: linux-kselftest@vger.kernel.org