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2022-10-11treewide: use prandom_u32_max() when possible, part 1Jason A. Donenfeld
Rather than incurring a division or requesting too many random bytes for the given range, use the prandom_u32_max() function, which only takes the minimum required bytes from the RNG and avoids divisions. This was done mechanically with this coccinelle script: @basic@ expression E; type T; identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; typedef u64; @@ ( - ((T)get_random_u32() % (E)) + prandom_u32_max(E) | - ((T)get_random_u32() & ((E) - 1)) + prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2) | - ((u64)(E) * get_random_u32() >> 32) + prandom_u32_max(E) | - ((T)get_random_u32() & ~PAGE_MASK) + prandom_u32_max(PAGE_SIZE) ) @multi_line@ identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; identifier RAND; expression E; @@ - RAND = get_random_u32(); ... when != RAND - RAND %= (E); + RAND = prandom_u32_max(E); // Find a potential literal @literal_mask@ expression LITERAL; type T; identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; position p; @@ ((T)get_random_u32()@p & (LITERAL)) // Add one to the literal. @script:python add_one@ literal << literal_mask.LITERAL; RESULT; @@ value = None if literal.startswith('0x'): value = int(literal, 16) elif literal[0] in '123456789': value = int(literal, 10) if value is None: print("I don't know how to handle %s" % (literal)) cocci.include_match(False) elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1: print("Skipping 0x%x for cleanup elsewhere" % (value)) cocci.include_match(False) elif value & (value + 1) != 0: print("Skipping 0x%x because it's not a power of two minus one" % (value)) cocci.include_match(False) elif literal.startswith('0x'): coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1)) else: coccinelle.RESULT = cocci.make_expr("%d" % (value + 1)) // Replace the literal mask with the calculated result. @plus_one@ expression literal_mask.LITERAL; position literal_mask.p; expression add_one.RESULT; identifier FUNC; @@ - (FUNC()@p & (LITERAL)) + prandom_u32_max(RESULT) @collapse_ret@ type T; identifier VAR; expression E; @@ { - T VAR; - VAR = (E); - return VAR; + return E; } @drop_var@ type T; identifier VAR; @@ { - T VAR; ... when != VAR } Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Yury Norov <yury.norov@gmail.com> Reviewed-by: KP Singh <kpsingh@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd Acked-by: Jakub Kicinski <kuba@kernel.org> Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390 Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2018-11-30test_hexdump: use memcpy instead of strncpyLinus Torvalds
New versions of gcc reasonably warn about the odd pattern of strncpy(p, q, strlen(q)); which really doesn't make sense: the strncpy() ends up being just a slow and odd way to write memcpy() in this case. Apparently there was a patch for this floating around earlier, but it got lost. Acked-again-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22lib/test_hexdump.c: fix failure on big endian cpuChristophe Leroy
On a big endian cpu, test_hexdump fails as follows. The logs show that bytes are expected in reversed order. [...] test_hexdump: Len: 24 buflen: 130 strlen: 97 test_hexdump: Result: 97 'be32db7b 0a1893b2 70bac424 7d83349b a69c31ad 9c0face9 .2.{....p..$}.4...1.....' test_hexdump: Expect: 97 '7bdb32be b293180a 24c4ba70 9b34837d ad319ca6 e9ac0f9c .2.{....p..$}.4...1.....' test_hexdump: Len: 8 buflen: 130 strlen: 77 test_hexdump: Result: 77 'be32db7b0a1893b2 .2.{....' test_hexdump: Expect: 77 'b293180a7bdb32be .2.{....' test_hexdump: Len: 6 buflen: 131 strlen: 87 test_hexdump: Result: 87 'be32 db7b 0a18 .2.{..' test_hexdump: Expect: 87 '32be 7bdb 180a .2.{..' test_hexdump: Len: 24 buflen: 131 strlen: 97 test_hexdump: Result: 97 'be32db7b 0a1893b2 70bac424 7d83349b a69c31ad 9c0face9 .2.{....p..$}.4...1.....' test_hexdump: Expect: 97 '7bdb32be b293180a 24c4ba70 9b34837d ad319ca6 e9ac0f9c .2.{....p..$}.4...1.....' test_hexdump: Len: 32 buflen: 131 strlen: 101 test_hexdump: Result: 101 'be32db7b0a1893b2 70bac4247d83349b a69c31ad9c0face9 4cd1199943b1af0c .2.{....p..$}.4...1.....L...C...' test_hexdump: Expect: 101 'b293180a7bdb32be 9b34837d24c4ba70 e9ac0f9cad319ca6 0cafb1439919d14c .2.{....p..$}.4...1.....L...C...' test_hexdump: failed 801 out of 1184 tests This patch fixes it. Link: http://lkml.kernel.org/r/f3112437f62c2f48300535510918e8be1dceacfb.1533610877.git.christophe.leroy@c-s.fr Fixes: 64d1d77a44697 ("hexdump: introduce test suite") Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: rashmica <rashmicy@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: print statistics at the endAndy Shevchenko
Like others test are doing print the gathered statistics after test module is finished. Return from the module based on the result. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: test all possible group sizes for overflowAndy Shevchenko
Currently the only one combination is tested for overflow, i.e. rowsize = 16, groupsize = 1, len = 1. Do various test to go through all possible branches. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: check all bytes in real bufferAndy Shevchenko
After processing by hex_dump_to_buffer() check all the parts to be expected. Part 1. The actual expected hex dump with or without ASCII part. Part 2. Check if the buffer is dirty beyond needed. Part 3. Return code should be as expected. This is done by using comparison of the return code and memcmp() against the test buffer. We fill the buffer by FILL_CHAR ('#') characters, so, we expect to have a tail of the buffer will be left untouched. The terminating NUL is also checked by memcmp(). Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: switch to memcmp()Andy Shevchenko
Better to use memcmp() against entire buffer to check that nothing is happened to the data in the tail. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: replace magic numbers by their meaningAndy Shevchenko
The magic numbers of the length are converted to their actual meaning, such as end of the buffer with and without ASCII part. We don't touch the rest of the magic constants that will be removed in the following commits. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: go through all possible lengths of bufferAndy Shevchenko
When test for overflow do iterate the buffer length in a range 0 .. BUF_SIZE. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: define FILL_CHAR constantAndy Shevchenko
Define a character to fill the test buffers. Though the character should be printable since it's used when errors are reported. It should neither be from hex digit [a-fA-F0-9] dictionary nor space. It is recommended not to use one which is present in ASCII part of the test data. Later on we might switch to unprintable character to make test case more robust. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: introduce test_hexdump_prepare_test() helperAndy Shevchenko
The function prepares the expected result in the provided buffer. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20test_hexdump: rename to test_hexdumpAndy Shevchenko
The test suite currently doesn't cover many corner cases when hex_dump_to_buffer() runs into overflow. Refactor and amend test suite to cover most of the cases. This patch (of 9): Just to follow the scheme that most of the test modules are using. There is no fuctional change. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>