Bug 1371487 - RPM: OOB read in headerSigVerify()
Summary: RPM: OOB read in headerSigVerify()
Alias: None
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
(Show other bugs)
Version: unspecified
Hardware: All Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Whiteboard: impact=low,public=20160902,reported=2...
Keywords: Security
Depends On: 1372685 1373107
Blocks: 1357448
TreeView+ depends on / blocked
Reported: 2016-08-30 10:14 UTC by Cedric Buissart
Modified: 2017-01-24 11:07 UTC (History)
3 users (show)

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Last Closed: 2017-01-24 11:07:34 UTC
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RHEL 7.3 requirements from Atomic Host:
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Description Cedric Buissart 2016-08-30 10:14:48 UTC
A heap based out-of-bound (OOB) read was discovered in RPM headerSigVerify() function, when doing a sanity check of the RPM headers. An attacker could trick a system administrator into reading a specially crafted RPM file, resulting in the crash of the RPM command.
The OOB read happens before the signature verification, thus the RPM does not need to be signed for the OOB to happen.

Upstream fix :

Comment 1 Cedric Buissart 2016-08-30 10:14:53 UTC

Name: Francisco Alonso

Comment 2 Cedric Buissart 2016-08-30 10:24:53 UTC
Valgrind backtrace:

==11445== Invalid read of size 8   
==11445==    at 0x4C2E25E: memcpy@@GLIBC_2.14 (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==11445==    by 0x4E62530: UnknownInlinedFun (string3.h:51)
==11445==    by 0x4E62530: headerSigVerify (package.c:240)
==11445==    by 0x4E62530: headerVerify (package.c:363)
==11445==    by 0x4E62915: rpmpkgReadHeader (package.c:457)
==11445==    by 0x4E62BEA: rpmpkgRead (package.c:578)
==11445==    by 0x4E6352D: rpmReadPackageFile (package.c:717)
==11445==    by 0x4E6EB81: rpmgiReadHeader (rpmgi.c:90)
==11445==    by 0x4E6EB81: rpmgiLoadReadHeader (rpmgi.c:126)
==11445==    by 0x4E6EB81: rpmgiNext (rpmgi.c:216)
==11445==    by 0x4E671D8: rpmgiShowMatches (query.c:274)
==11445==    by 0x4E671D8: rpmcliArgIter (query.c:518)
==11445==    by 0x4E672A6: rpmcliQuery (query.c:568)
==11445==    by 0x401918: main (rpmqv.c:304)

Vulnerable code :
sigtd.data = memcpy(xmalloc(siglen), dataStart + info.offset, siglen);

While sanity checking a SHA1HEADER, RSAHEADER or DSAHEADER tag entry, there is no check that 'dataStart + info.offset + siglen' remains in the malloc'ed boundary.

Comment 3 Cedric Buissart 2016-09-02 11:29:39 UTC
Created rpm tracking bugs for this issue:

Affects: fedora-all [bug 1372685]

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