[SCSI] aacraid: fix panic on short Inquiry

Unable to handle kernel paging request at ffff8101c0000000 RIP:
 [<ffffffff880b22a1>] :aacraid:aac_internal_transfer+0xd6/0xe3
PGD 8063 PUD 0
Oops: 0000 [1] SMP
last sysfs file: /block/sdb/removable
CPU 2
Modules linked in: autofs4(U) hidp(U) nfs(U) lockd(U)
fscache(U) nfs_acl(U) rfcomm(U) l2cap(U) bluetooth(U)
sunrpc(U) ipv6(U) cpufreq_ondemand(U) dm_mirror(U) dm_mod(U)
video(U) sbs(U) i2c_ec(U) button(U) battery(U) asus_acpi(U)
acpi_memhotplug(U) ac(U) parport_pc(U) lp(U) parport(U)
joydev(U) ide_cd(U) i2c_i801(U) i2c_core(U) shpchp(U)
cdrom(U) bnx2(U) sg(U) pcspkr(U) ata_piix(U) libata(U)
aacraid(U) sd_mod(U) scsi_mod(U) ext3(U) jbd(U) ehci_hcd(U)
ohci_hcd(U) uhci_hcd(U)
Pid: 2352, comm: syslogd Not tainted 2.6.18-prep #1
RIP: 0010:[<ffffffff880b22a1>]  [<ffffffff880b22a1>] :aacraid:aac_internal_transfer+0xd6/0xe3
RSP: 0000:ffff8101bfd1fe68  EFLAGS: 00010083
RAX: 0000000000000063 RBX: 0000000000000008 RCX: 00000000ffd1fea0
RDX: ffffffff802da628 RSI: ffff8101c0000000 RDI: ffff8101b2a08168
RBP: ffff8101b2728010 R08: ffffffff802da628 R09: 0000000000000046
R10: 0000000000000000 R11: 0000000000000080 R12: 0000000000000010
R13: ffff8101bfd1fea8 R14: ffff8101bc74df58 R15: ffff8101bc74df58
FS:  00002aaaab0146f0(0000) GS:ffff8101bfcd2e40(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: ffff8101c0000000 CR3: 00000001bdecd000 CR4: 00000000000006e0
Process syslogd (pid: 2352, threadinfo ffff8101bc74c000, task ffff8101bd979040)
Stack:  0000000000000012 0000000000000036 0000000000000000 ffff8101bee9a800
 ffff8101be9d3a00 ffff8101be9d3a00 ffff8101be8014f8 ffffffff880b26cc
 40212227607e3141 2029282a26252423 0000000000000003 ffff810037e3a000
Call Trace:
 <IRQ [<ffffffff880b26cc>] :aacraid:get_container_name_callback+0x8b/0xb5
 [<ffffffff880b6f67>] :aacraid:aac_intr_normal+0x1b3/0x1f9
 [<ffffffff880b8007>] :aacraid:aac_rkt_intr+0x37/0x115
 [<ffffffff80099749>] __rcu_process_callbacks+0xf8/0x1a8
 [<ffffffff80010705>] handle_IRQ_event+0x29/0x58
 [<ffffffff800b2fe0>] __do_IRQ+0xa4/0x105
 [<ffffffff80011c19>] __do_softirq+0x5e/0xd5
 [<ffffffff8006a193>] do_IRQ+0xe7/0xf5
 [<ffffffff8005b649>] ret_from_intr+0x0/0xa

On digging into it, it turned out that the customer was probing an
aacraid device with an INQUIRY of 8 bytes.  The way aacraid works, it
was blindly trying to use aac_internal_transfer to copy the container
name to byte 16 of the inquiry data, resulting in a negative transfer
length.  It then copies over the whole of kernel memory before
dropping off the end.

Fix updated and corrected by Mark Salyzyn

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/aacraid/aachba.c

@@ -340,7 +340,7 @@ int aac_get_containers(struct aac_dev *dev)
 static void aac_internal_transfer(struct scsi_cmnd *scsicmd, void *data, unsigned int offset, unsigned int len)
 {
 	void *buf;
-	unsigned int transfer_len;
+	int transfer_len;
 	struct scatterlist *sg = scsicmd->request_buffer;
 
 	if (scsicmd->use_sg) {
@@ -351,7 +351,7 @@ static void aac_internal_transfer(struct scsi_cmnd *scsicmd, void *data, unsigne
 		transfer_len = min(scsicmd->request_bufflen, len + offset);
 	}
 	transfer_len -= offset;
-	if (buf && transfer_len)
+	if (buf && transfer_len > 0)
 		memcpy(buf + offset, data, transfer_len);
 
 	if (scsicmd->use_sg)