linux-kernel - Stack buffer size issue

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <48D249D4.8000400@gmail.com>
Date:	Thu, 18 Sep 2008 14:30:12 +0200
From:	evilsocket <evilsocket@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Stack buffer size issue

Hello to all, i'm trying to develop a kernel module that accepts an 
ioctl with this structure :

typedef struct{
    /* [INPUT]  */
    long   process;
    unsigned long address;
   
    /* [OUTPUT] */   
    long mm_size;
}
mg_query_t;

where :

process : is the pid of a process .
address : is the address of a buffer on the stack of that process .

mm_size : *should* be the return value of the ioctl, indicating the size 
of that buffer, as an example (userspace test application):

char * abuffer[123];
mg_query_t query;
   
query.process = getpid();
query.address = abuffer;
   
if( ioctl( fd, IOCTL_MTABLE_BY_PID, &query ) < 0 ){
    close(fd);
    perror( "IOCTL_MTABLE_BY_PID" );
    return -1;
}

printf( "SIZE : %d\n", query.mm_size );



This *should* give the output :

SIZE : 123

I'm using the struct task_struct in the kernel module, looping the mmap 
to find the vm area the address resides in and then to set

mm_size = vm_end - vm_start

But doing so i obtaing only the size of the vm page the buffer resides .

Any hints ?

Thanks in advantage .
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/