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Message-ID: <CACn5sdRFRE-eTpgGdJr8hok0phUFtXHGAF_k3OAe1R46a1Nv9g@mail.gmail.com>
Date: Sun, 25 Oct 2015 23:34:27 +0100
From: Gustavo Grieco <gustavo.grieco@...il.com>
To: oss-security@...ts.openwall.com
Subject: Pointer misuse unziping files with busybox

Unziping a specially crafted zip file results in a computation of an invalid
pointer and a crash reading an invalid address. Upstream is taking a look
to it, but in the meantime if someone wants to provide some feedback, it
will be nice. Find an attached a test case to reproduce it. A
complete backtrace in busybox 1.21 (debug) is available here:

$ gdb --args ./busybox_unstripped unzip x.-6170921383890712452
...
(gdb) run
Starting program: /home/g/Code/busybox-1.21.0/busybox_unstripped unzip
x.-6170921383890712452
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Archive:  x.-6170921383890712452
  inflating: ]3j½r«I..K-%Ix

Program received signal SIGSEGV, Segmentation fault.
huft_build (b=b@...ry=0x7fffffffd320, n=n@...ry=264, s=s@...ry=257,
d=d@...ry=0x5fa900 <cplens>, e=e@...ry=0x5fa8c0 <cplext> "",
t=0x60620000eb08,
    t@...ry=0x602c0000fe60, m=0x7fffffffd260) at
archival/libarchive/decompress_gunzip.c:441
441                    r.e = (unsigned char) e[*p - s]; /* non-simple--look
up
in lists */
(gdb) bt
#0  huft_build (b=b@...ry=0x7fffffffd320, n=n@...ry=264, s=s@...ry=257,
d=d@...ry=0x5fa900 <cplens>, e=e@...ry=0x5fa8c0 <cplext> "",
    t=0x60620000eb08, t@...ry=0x602c0000fe60, m=0x7fffffffd260) at
archival/libarchive/decompress_gunzip.c:441
#1  0x0000000000520b52 in inflate_block (state=state@...ry=0x602c0000fe00,
e=e@...ry=0x602c0000fe83 "") at archival/libarchive/decompress_gunzip.c:905
#2  0x00000000005222d1 in inflate_get_next_window (state=0x602c0000fe00) at
archival/libarchive/decompress_gunzip.c:947
#3  inflate_unzip_internal (state=state@...ry=0x602c0000fe00, in=in@...ry=3,
out=out@...ry=4) at archival/libarchive/decompress_gunzip.c:1004
#4  0x0000000000522a6a in inflate_unzip (aux=aux@...ry=0x7fffffffdc30,
in=in@...ry=3, out=out@...ry=4) at
archival/libarchive/decompress_gunzip.c:1048
#5  0x000000000051b255 in unzip_extract (dst_fd=4,
zip_header=0x7fffffffdd50)
at archival/unzip.c:255
#6  unzip_main (argc=<optimized out>, argv=<optimized out>) at
archival/unzip.c:654
#7  0x00000000004088bd in run_applet_no_and_exit
(applet_no=applet_no@...ry=328, argv=argv@...ry=0x7fffffffe170) at
libbb/appletlib.c:759
#8  0x0000000000408935 in run_applet_and_exit (name=0x7fffffffe4c8 "unzip",
argv=argv@...ry=0x7fffffffe170) at libbb/appletlib.c:766
#9  0x0000000000408e7c in busybox_main (argv=0x7fffffffe170) at
libbb/appletlib.c:728
#10 run_applet_and_exit (name=<optimized out>, argv=argv@...ry
=0x7fffffffe168)
at libbb/appletlib.c:768
#11 0x0000000000408f65 in main (argc=<optimized out>, argv=0x7fffffffe168)
at
libbb/appletlib.c:823

(gdb) x/i $rip
=> 0x51fb17 <huft_build+2852>:    mov    (%rdi),%dl
(gdb) info registers
rax            0x0    0
rbx            0x57    87
rcx            0x814a18    8473112
rdx            0x140900    1313024
rsi            0x5fa900    6269184
rdi            0xa04dcc    10505676
rbp            0x10007fff7940    0x10007fff7940
rsp            0x7fffffffc930    0x7fffffffc930
r8             0x7fffffffcb64    140737488341860
r9             0x7fffffffcbe8    140737488341992
r10            0x60620000eb10    105974023121680
r11            0x7fffffffcadc    140737488341724
r12            0x7fffffffd260    140737488343648
r13            0x8    8
r14            0x10007fff7944    17594333493572
r15            0x0    0
rip            0x51fb17    0x51fb17 <huft_build+2852>
eflags         0x10216    [ PF AF IF RF ]
cs             0x33    51
ss             0x2b    43
ds             0x0    0
es             0x0    0
fs             0x0    0
gs             0x0    0

This issue was discovered with QuickFuzz

Thanks!

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