| commit | 27ecd3f315a1ab08756208a6e6b2ef756d75ec63 | [log] [tgz] |
|---|---|---|
| author | Arthur Fabre <afabre@cloudflare.com> | Fri Jun 07 15:59:01 2019 +0100 |
| committer | Matt Layher <mdlayher@gmail.com> | Fri Jun 07 17:17:31 2019 +0000 |
| tree | 67b433a70d0cd49a98951675dbcc585e5522ffb1 | |
| parent | 1492cefac77f61bc789c00f41ead8f8d7307cd21 [diff] |
bpf: fix VM out of bounds LoadMemShift check
The bpf VM did not correctly check the bounds of LoadMemShift
instructions, as it used a size of 0 instead of the correct 1.
A LoadMemShift instruction 1 past the end of the input resulted in a
runtime panic:
panic(0x5c1d40, 0x7cec00)
/usr/local/go/src/runtime/panic.go:522 +0x1b5
golang.org/x/net/bpf.loadMemShift(...)
/home/afabre/go/pkg/mod/golang.org/x/net@v0.0.0-20190603091049-60506f45cf65/bpf/vm_instructions.go:137
golang.org/x/net/bpf.(*VM).Run(0xc00000ec40, 0xc0000173c8, 0x2, 0x8, 0x2, 0xc0000173c8, 0x0)
/home/afabre/go/pkg/mod/golang.org/x/net@v0.0.0-20190603091049-60506f45cf65/bpf/vm.go:131 +0xb0a
Fix this, and rework the out of bounds tests for load instructions to:
* Use an offset one past the end of the input, to catch this
* Use a filter that returns 1, to catch cases were the out of bounds
load does not cause a panic, but does not cause the VM to return 0.
Change-Id: I1e68886915207a34f59765805f907f36dc031f70
Reviewed-on: https://go-review.googlesource.com/c/net/+/180979
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matt Layher <mdlayher@gmail.com>
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