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author | Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com> | 2018-11-30 18:05:32 -0200 |
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committer | Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com> | 2018-11-30 18:05:32 -0200 |
commit | e5d262effe3a87164308a3f37e61b32d0348692a (patch) | |
tree | 2024005bb7e21dd547b7b25d0484c26b29bf43ee /math/test-math-no-finite.h | |
parent | 7e1d42400c1b8f03316fe14176133c8853cd3bbe (diff) | |
download | glibc-e5d262effe3a87164308a3f37e61b32d0348692a.tar.gz glibc-e5d262effe3a87164308a3f37e61b32d0348692a.tar.xz glibc-e5d262effe3a87164308a3f37e61b32d0348692a.zip |
Fix _dl_profile_fixup data-dependency issue (Bug 23690)
There is a data-dependency between the fields of struct l_reloc_result and the field used as the initialization guard. Users of the guard expect writes to the structure to be observable when they also observe the guard initialized. The solution for this problem is to use an acquire and release load and store to ensure previous writes to the structure are observable if the guard is initialized. The previous implementation used DL_FIXUP_VALUE_ADDR (l_reloc_result->addr) as the initialization guard, making it impossible for some architectures to load and store it atomically, i.e. hppa and ia64, due to its larger size. This commit adds an unsigned int to l_reloc_result to be used as the new initialization guard of the struct, making it possible to load and store it atomically in all architectures. The fix ensures that the values observed in l_reloc_result are consistent and do not lead to crashes. The algorithm is documented in the code in elf/dl-runtime.c (_dl_profile_fixup). Not all data races have been eliminated. Tested with build-many-glibcs and on powerpc, powerpc64, and powerpc64le. [BZ #23690] * elf/dl-runtime.c (_dl_profile_fixup): Guarantee memory modification order when accessing reloc_result->addr. * include/link.h (reloc_result): Add field init. * nptl/Makefile (tests): Add tst-audit-threads. (modules-names): Add tst-audit-threads-mod1 and tst-audit-threads-mod2. Add rules to build tst-audit-threads. * nptl/tst-audit-threads-mod1.c: New file. * nptl/tst-audit-threads-mod2.c: Likewise. * nptl/tst-audit-threads.c: Likewise. * nptl/tst-audit-threads.h: Likewise. Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Diffstat (limited to 'math/test-math-no-finite.h')
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