Fix OOB read in opcache POSIX largepage page-size selection#22429
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iliaal wants to merge 1 commit into
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Fix OOB read in opcache POSIX largepage page-size selection#22429iliaal wants to merge 1 commit into
iliaal wants to merge 1 commit into
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create_segments() under HAVE_SHM_CREATE_LARGEPAGE stored the int return of getpagesizes() in a size_t and iterated with a size_t counter. On the getpagesizes() error return (-1) the size_t became SIZE_MAX, passing the > 0 guard, and the unsigned loop counter made i >= 0 always true, so the loop ran from a huge index and read far outside the 3-element shared_segment_sindexes array; even on success, if no returned page size divided requested_size the counter wrapped past 0. Capture the result in a signed int and iterate signed so the error return is rejected and the loop terminates.
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create_segments() under HAVE_SHM_CREATE_LARGEPAGE stored the int return of getpagesizes() in a size_t and iterated with a size_t counter. On the getpagesizes() error return (-1) the size_t became SIZE_MAX, passing the > 0 guard, and the unsigned counter made i >= 0 always true, so the loop ran from a huge index and read far outside the 3-element shared_segment_sindexes array; even on success, if no returned page size divided requested_size the counter wrapped past 0. Capture the result in a signed int and iterate signed. This path is FreeBSD-only (HAVE_SHM_CREATE_LARGEPAGE), so it is not compiled or exercised on the Linux CI; the change is a type/sign correction within that block.