| commit | dfd613e0e4fd93ef945e9fbd6d42b79bcaf73905 | [log] [tgz] |
|---|---|---|
| author | Michael Anthony Knyszek <mknyszek@google.com> | Mon May 18 16:06:11 2020 +0000 |
| committer | Michael Knyszek <mknyszek@google.com> | Wed May 20 15:15:16 2020 +0000 |
| tree | 6e32f5f5f747a5eab4eea0e59d673ff1a36173c7 | |
| parent | 4ec4a792f6e60c9c4f40a928650c66419ee0e446 [diff] |
runtime: don't use (addrRange).subtract in removeGreaterEqual Currently in (*addrRanges).removeGreaterEqual we use (addrRange).subtract with a range from specified address to "infinity" which is supposed to be maxOffAddr. However, maxOffAddr is necessarily an inclusive bound on the address space, because on many platforms an exclusive bound would overflow back to 0. On some platforms like mips and mipsle, the address space is smaller than what's representable in a pointer, so if there's a range which hits the top of the address space (such as in the pageAlloc tests), the limit doesn't overflow, but maxOffAddr is inclusive, so any attempt to prune this range with (*addrRange).removeGreaterEqual causes a failure, since the range passed to subtract is contained within the address range which touches the top of the address space. Another problem with using subtract here is that addr and maxOffAddr.addr() may not be in the same segment which could cause makeAddrRange to panic. While this unlikely to happen, on some platforms such as Solaris it is possible. Fix these issues by not using subtract at all. Create a specific implementation of (addrRange).removeGreaterEqual which side-steps all of this by not having to worry about the top of the address space at all. Fixes #39128. Change-Id: Icd5b587b1a3d32a5681fb76cec4c001401f5756f Reviewed-on: https://go-review.googlesource.com/c/go/+/234457 Reviewed-by: Michael Pratt <mpratt@google.com> Reviewed-by: Austin Clements <austin@google.com> Reviewed-by: Cherry Zhang <cherryyz@google.com>
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