diff options
| author | Cornelia Huck <cornelia.huck@de.ibm.com> | 2016-08-15 11:10:28 +0200 |
|---|---|---|
| committer | Cornelia Huck <cornelia.huck@de.ibm.com> | 2016-09-05 15:15:16 +0200 |
| commit | 882b3b97697affb36ca3d174f42f846232008979 (patch) | |
| tree | ea3362a34f6f6d6390ec5c13dca304a7ecf16a3b /hw/s390x | |
| parent | 5759db1936b52a7f5d0cd4e1377ed74054d555f9 (diff) | |
s390x/css: handle cssid 255 correctly
The cssid 255 is reserved but still valid from an architectural
point of view. However, feeding a bogus schid of 0xffffffff into
the virtio hypercall will lead to a crash:
Stack trace of thread 138363:
#0 0x00000000100d168c css_find_subch (qemu-system-s390x)
#1 0x00000000100d3290 virtio_ccw_hcall_notify
#2 0x00000000100cbf60 s390_virtio_hypercall
#3 0x000000001010ff7a handle_hypercall
#4 0x0000000010079ed4 kvm_cpu_exec (qemu-system-s390x)
#5 0x00000000100609b4 qemu_kvm_cpu_thread_fn
#6 0x000003ff8b887bb4 start_thread (libpthread.so.0)
#7 0x000003ff8b78df0a thread_start (libc.so.6)
This is because the css array was only allocated for 0..254
instead of 0..255.
Let's fix this by bumping MAX_CSSID to 255 and fencing off the
reserved cssid of 255 during css image allocation.
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Diffstat (limited to 'hw/s390x')
| -rw-r--r-- | hw/s390x/css.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/hw/s390x/css.c b/hw/s390x/css.c index bb8e4be339..b0e81efc27 100644 --- a/hw/s390x/css.c +++ b/hw/s390x/css.c @@ -141,7 +141,8 @@ out_err: int css_create_css_image(uint8_t cssid, bool default_image) { trace_css_new_image(cssid, default_image ? "(default)" : ""); - if (cssid > MAX_CSSID) { + /* 255 is reserved */ + if (cssid == 255) { return -EINVAL; } if (channel_subsys.css[cssid]) { @@ -1267,7 +1268,7 @@ bool css_schid_final(int m, uint8_t cssid, uint8_t ssid, uint16_t schid) uint8_t real_cssid; real_cssid = (!m && (cssid == 0)) ? channel_subsys.default_cssid : cssid; - if (real_cssid > MAX_CSSID || ssid > MAX_SSID || + if (ssid > MAX_SSID || !channel_subsys.css[real_cssid] || !channel_subsys.css[real_cssid]->sch_set[ssid]) { return true; @@ -1282,9 +1283,6 @@ static int css_add_virtual_chpid(uint8_t cssid, uint8_t chpid, uint8_t type) CssImage *css; trace_css_chpid_add(cssid, chpid, type); - if (cssid > MAX_CSSID) { - return -EINVAL; - } css = channel_subsys.css[cssid]; if (!css) { return -EINVAL; |