Fix out-of-bound access in ip6addr_ntoa_r() #29
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sfionov
commented
Mar 7, 2024
| break; | ||
| } | ||
| if (empty_block_flag == 0) { | ||
| } else if (empty_block_flag == 0) { | ||
| /* generate empty block "::", but only if more than one contiguous zero block, | ||
| * according to current formatting suggestions RFC 5952. */ | ||
| next_block_value = lwip_htonl(addr->addr[(current_block_index + 1) >> 1]); |
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Out-of-bounds access is happened here.
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The updated test is still passing when skipping the ip6_addr code change. Can you split into a commit with a failing test and then the change that fixes it? |
When detecting that zero is single, code reads the next group even if current group is last group. If next bytes are not-null, last zero is not omitted. If next bytes are null, last zero is omitted, but since there are no groups left, finishing ':' will not be written, resulting in invalid address. This commit turns off non-single zero check for the last group.
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@yarrick Done, split into two commits |
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The test still passes when applied on top of the current code |
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@yarrick What platform do you use? I originally detected this issue when arm64 musl-gcc 13.2 refused to compile code with -Wall -Wextra. And test fails on arm64 macOS without patch. |
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I run on Linux on x86_64 (Fedora 40) |
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When detecting that zero is single, code reads the next group even if current group is last group.
If next bytes are non-null, last zero is not omitted.
If next bytes are null, last zero is omitted, but since there are no groups left, finishing ':' will not be written, resulting in invalid address.
This commit turns off non-single zero check for the last group.