Fix huge_ralloc() race when using mremap(2).
Fix huge_ralloc() to remove the old memory region from tree of huge allocations *before* calling mremap(2), in order to make sure that no other thread acquires the old memory region via mmap() and encounters stale metadata in the tree. Reported by: Rich Prohaska
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parent
45e040a82c
commit
03bf7a7a26
12
src/huge.c
12
src/huge.c
@ -234,6 +234,13 @@ huge_ralloc(void *ptr, size_t oldsize, size_t size, size_t extra,
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) {
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size_t newsize = huge_salloc(ret);
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/*
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* Remove ptr from the tree of huge allocations before
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* performing the remap operation, in order to avoid the
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* possibility of another thread acquiring that mapping before
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* this one removes it from the tree.
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*/
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huge_dalloc(ptr, false);
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if (mremap(ptr, oldsize, newsize, MREMAP_MAYMOVE|MREMAP_FIXED,
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ret) == MAP_FAILED) {
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/*
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@ -253,9 +260,8 @@ huge_ralloc(void *ptr, size_t oldsize, size_t size, size_t extra,
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if (opt_abort)
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abort();
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memcpy(ret, ptr, copysize);
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idalloc(ptr);
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} else
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huge_dalloc(ptr, false);
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chunk_dealloc(ptr, oldsize);
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}
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} else
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#endif
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{
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