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Date: Fri, 27 Dec 2013 18:35:00 +0000 (UTC)
From: David Wuertele <>
Subject: NULL deref SEGV in malloc.c:unbin()

I wonder if anyone has hit this before?   In unbin(), c->next->prev is set, but
c->next is NULL.   It happens repeatedly, and here's what gdb says:

(gdb) b fopen
Breakpoint 9 at 0x90f78: file src/stdio/fopen.c, line 13.
(gdb) c

Breakpoint 9, fopen (filename=0xaabe4 "/etc/hosts", mode=0xaabf0 "r")
    at src/stdio/fopen.c:13
13	src/stdio/fopen.c: No such file or directory.
	in src/stdio/fopen.c
(gdb) b unbin
Breakpoint 10 at 0x8bc44: file src/malloc/malloc.c, line 239.
(gdb) c

Breakpoint 10, unbin (c=0x21408b8, i=40) at src/malloc/malloc.c:239
239	src/malloc/malloc.c: No such file or directory.
	in src/malloc/malloc.c
(gdb) print *c
$6 = {psize = 2096, csize = 2097, next = 0x2140088, prev = 0x0}
(gdb) s
241	in src/malloc/malloc.c
Program received signal SIGSEGV, Segmentation fault.
0x0008bcc0 in unbin (c=0x21408b8, i=40) at src/malloc/malloc.c:241
241	in src/malloc/malloc.c

The root cause was not obvious on scanning the source.
Is this perhaps something that's already been fixed?


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