lwIP - A Lightweight TCP/IP stack - Bugs: bug #57376, Assertion "inconsistent...
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bug #57376: Assertion "inconsistent oversize vs. space" failed
Submitter: | Hiromasa Ito <vhertz> | ||
Submitted: | Sat 07 Dec 2019 01:15:12 PM UTC | ||
Category: | TCP | Severity: | 3 - Normal |
Item Group: | Crash Error | Status: | None |
Privacy: | Public | Assigned to: | None |
Open/Closed: | Open | Planned Release: | None |
lwIP version: | Other |
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Corresponding source code
Hi, all.
This is one of the assertion failures I found by fuzzing (to lwIP ver2.1.0.RC1).
The following LWIP_ASSERT() at lwip/src/core/tcp_out.c:504 fails.
From my point of view, this is caused by an incoming packet set MSS.
Before checking this assertion, the value of `space` and `oversize` are set as below:
The value of `space` depends on MSS when tcp_write() is called.
On the other hand, the value of `oversize` depends on `pcb->unsent_oversize` only.
In lwIP, incoming packets can change the MSS at an arbitrary timing.
As a result, the assertion can fail.
You can reproduce this failure with 'crashed_inputs/005' attached to the following message of lwip-devel:
https://lists.nongnu.org/archive/html/lwip-devel/2019-12/msg00013.html