Bug 1663907 (CVE-2018-20535) - CVE-2018-20535 nasm: Use-after-free at asm/preproc.c resulting in a denial of service
Summary: CVE-2018-20535 nasm: Use-after-free at asm/preproc.c resulting in a denial of...
Keywords:
Status: ASSIGNED
Alias: CVE-2018-20535
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Nobody
QA Contact:
URL:
Whiteboard:
Depends On: 1663909 1671502 1671503
Blocks: 1663910
TreeView+ depends on / blocked
 
Reported: 2019-01-07 09:53 UTC by Andrej Nemec
Modified: 2023-07-07 08:35 UTC (History)
4 users (show)

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Description Andrej Nemec 2019-01-07 09:53:43 UTC 
A use-after-free vulnerability was found in nasm. A specially crafted file could cause the application to crash.

Upstream issue:

https://bugzilla.nasm.us/show_bug.cgi?id=3392530
Comment 1 Andrej Nemec 2019-01-07 09:54:59 UTC 
Created nasm tracking bugs for this issue:

Affects: fedora-all [bug 1663909]
Comment 2 Nick Clifton 2019-01-17 10:37:38 UTC 
Setting devel cond NAK - waiting on upstream fix.
Comment 3 Scott Gayou 2019-01-31 18:18:33 UTC 
Red Hat Enterprise 6 and 7 are vulnerable. Valgrind output matches upstream's ASAN output relatively well:

```
poc:15: error: label or instruction expected at start of line
poc:16: error: attempt to define a local label before any non-local labels
poc:18: error: parser: instruction expected
poc:18: error: parser: instruction expected
poc:18: error: label or instruction expected at start of line
==12504== Invalid read of size 4
==12504==    at 0x4346C5: pp_getline (preproc.c:4957)
==12504==    by 0x4046E3: assemble_file.constprop.3 (nasm.c:1222)
==12504==    by 0x402D02: main (nasm.c:463)
```
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