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From: "r3tr0spect2019 at gmail dot com" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug c++/29166] New: `demangle_const` causes infinite recursion and stack overflow
Date: Sat, 21 May 2022 17:23:54 +0000 [thread overview]
Message-ID: <bug-29166-4717@http.sourceware.org/bugzilla/> (raw)
https://sourceware.org/bugzilla/show_bug.cgi?id=29166
Bug ID: 29166
Summary: `demangle_const` causes infinite recursion and stack
overflow
Product: gdb
Version: HEAD
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c++
Assignee: unassigned at sourceware dot org
Reporter: r3tr0spect2019 at gmail dot com
Target Milestone: ---
Original Post: `https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105115`
The bug is similar to CVE-2021-3530, which was reported here:
`https://bugs.launchpad.net/ubuntu/+source/binutils/+bug/1925348`.
Commit: `e84412c6a3c3eed1a4eca5fe18f329bfa7efea40` at
`https://github.com/bminor/binutils-gdb`.
The simplified PoC:
$ echo _RYAbB2_ | ./binutils/cxxfilt
Segmentation fault
Root Cause Analysis:
1. In `rust_demangle_callback`, "_R" at beginning causes `rdm.version ==
0`[1][2], so `demangle_path` in the else-branch is called[3] with `rdm.sym ==
"YAbB2_"`, with `rdm.next` field initialized to 0.
2. Next char 'Y' causes `demangle_type` to be called[4] in a switch-case
branch, with `rdm.next == 1`.
3. Next char 'A' causes `demangle_type` to be called first[5] to consume char
'b', then `demangle_const` is called[6] with `rdm.next == 3`.
4. Next char 'B' is consumed[7], and "2_" is parsed as `integer_62`[8] to be
value 3, and this vlaue is assigned to `rdm.next`, then `demangle_const` is
called recursively[9]. However, currently the situation is `rdm.next == 3`
again, which is exactly same as last call to `demangle_const`, and this causes
infinite recursion.
[1] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L1356
[2] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L1362
[3] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L1453
[4] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L759
[5] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L934
[6] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L938
[7] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L1151
[8] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L1153
[9] 626d0e40e55c35a4f143b70def498734e8ed3c2a/libiberty/rust-demangle.c#L1158
Possible Fix:
The infinite recursion check added in this
[commit](https://github.com/bminor/binutils-gdb/commit/f10f8617a302f45dae721eae0cd659911f03d864)
should also be applied to `demangle_const`
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next reply other threads:[~2022-05-21 17:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-21 17:23 r3tr0spect2019 at gmail dot com [this message]
2022-05-21 17:24 ` [Bug c++/29166] " r3tr0spect2019 at gmail dot com
2022-05-21 17:50 ` schwab@linux-m68k.org
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