Bug 1223095
| Summary: | access to uninitialized memory in getaddrinfo if nscd is running | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Paulo Andrade <pandrade> | ||||
| Component: | glibc | Assignee: | Florian Weimer <fweimer> | ||||
| Status: | CLOSED ERRATA | QA Contact: | Sergey Kolosov <skolosov> | ||||
| Severity: | medium | Docs Contact: | Mark Flitter <mflitter> | ||||
| Priority: | medium | ||||||
| Version: | 6.5 | CC: | anrussel, ashankar, codonell, fweimer, mcermak, mflitter, mnewsome, pfrankli, sauchter, skolosov, thomas.oulevey | ||||
| Target Milestone: | rc | ||||||
| Target Release: | --- | ||||||
| Hardware: | All | ||||||
| OS: | All | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||
| Doc Text: |
Resolution for getaddrinfo accessing uninitialised data
On systems with nscd enabled, the getaddrinfo function in glibc could access uninitialized data and return false address information.
This update avoids accessing uninitialized data and ensures that correct addresses are returned.
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Story Points: | --- | ||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2017-03-21 10:34:44 UTC | Type: | Bug | ||||
| Regression: | --- | Mount Type: | --- | ||||
| Documentation: | --- | CRM: | |||||
| Verified Versions: | Category: | --- | |||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||
| Embargoed: | |||||||
| Bug Depends On: | |||||||
| Bug Blocks: | 1172231, 1269194, 1361283 | ||||||
| Attachments: |
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Created attachment 1027400 [details]
gaitest.c
Test case.
strace will show random values, like this:
connect(3, {sa_family=XXX /* AF_??? */, sa_data="\0\0\377\177\0\0\0\0\0\0\0\0\0\0"}, 16) = -1 EAFNOSUPPORT (Address family not supported by protocol)
where XXX is some random value.
Valgrind will tell all sorts of uninitialized memory use.
Moving this to rhel-6.8 since we're outside the rhel-6.7 development window. We'll have to look at this more carefully and decide how to fix it. I can confirm that the upstream fix addresses this issue:
commit a071766ebfd853179ac39f9773f894029bf86d36
Author: Andreas Schwab <schwab>
Date: Thu Mar 20 15:05:25 2014 +0100
Fix use of half-initialized result in getaddrinfo when using nscd (bug 16743)
This fixes a bug in the way the results from __nscd_getai are collected:
for every returned result a new entry is first added to the
gaih_addrtuple list, but if that result doesn't match the request this
entry remains uninitialized. So for this non-matching result an extra
result with uninitialized content is returned.
To reproduce (with nscd running):
$ getent ahostsv4 localhost
127.0.0.1 STREAM localhost
127.0.0.1 DGRAM
127.0.0.1 RAW
(null) STREAM
(null) DGRAM
(null) RAW
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a071766ebfd853179ac39f9773f894029bf86d36
This bug was accidentally moved from POST to MODIFIED via an error in automation, please see mmccune with any questions Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHSA-2017-0680.html |
The problem also happens in rhel-7.x. Checking in rhel-7, the memory is allocated at: sysdeps/posix/getaddrinfo.c:706 if (__libc_use_alloca (alloca_used + air->naddrs * sizeof (struct gaih_addrtuple))) addrmem = alloca_account (air->naddrs * sizeof (struct gaih_addrtuple), alloca_used); Simple debug attaching gdb from valgrind: ==30081== Conditional jump or move depends on uninitialised value(s) ==30081== at 0x4F10C22: gaih_inet (getaddrinfo.c:1200) ==30081== by 0x4F147AC: getaddrinfo (getaddrinfo.c:2420) ==30081== by 0x4005C8: main (gaitest.c:10) ... (gdb) bt #0 gaih_inet (name=name@entry=0x400660 "localhost", service=<optimized out>, req=req@entry=0xffefffd30, pai=0x51f62a8, pai@entry=0xffefffbe0, naddrs=naddrs@entry=0xffefffbd0) at ../sysdeps/posix/getaddrinfo.c:1200 #1 0x0000000004f147ad in __GI_getaddrinfo (name=0x400660 "localhost", service=0x0, hints=0xffefffd30, pai=0xffefffd68) at ../sysdeps/posix/getaddrinfo.c:2420 #2 0x00000000004005c9 in main () at gaitest.c:10 (gdb) p addrmem $1 = (struct gaih_addrtuple *) 0xffefff8b0 (gdb) p at->next $2 = (struct gaih_addrtuple *) 0xffefff8b0 (gdb) p* at->next $3 = {next = 0x0, name = 0x0, family = -16778416, addr = {15, 0, 0, 0}, scopeid = 0} (gdb) p* req $4 = {ai_flags = 2, ai_family = 2, ai_socktype = 0, ai_protocol = 0, ai_addrlen = 0, ai_addr = 0x0, ai_canonname = 0x0, ai_next = 0x0} (gdb) p $rsp $5 = (void *) 0xffefff890