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Subject[PATCH v2] xen/hvc: replace BUG_ON() with negative return value
Date
Xen frontends shouldn't BUG() in case of illegal data received from
their backends. So replace the BUG_ON()s when reading illegal data from
the ring page with negative return values.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- drop BUG_ON() (Christophe Leroy, Greg Kroah-Hartmann)
- replace WARN_ONCE() by pr_err_once() (Greg Kroah-Hartmann)
- break out from original series
---
drivers/tty/hvc/hvc_xen.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 92c9a476defc..8f143c09a169 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -86,7 +86,11 @@ static int __write_console(struct xencons_info *xencons,
cons = intf->out_cons;
prod = intf->out_prod;
mb(); /* update queue values before going on */
- BUG_ON((prod - cons) > sizeof(intf->out));
+
+ if ((prod - cons) > sizeof(intf->out)) {
+ pr_err_once("xencons: Illegal ring page indices");
+ return -EINVAL;
+ }

while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
@@ -114,7 +118,10 @@ static int domU_write_console(uint32_t vtermno, const char *data, int len)
*/
while (len) {
int sent = __write_console(cons, data, len);
-
+
+ if (sent < 0)
+ return sent;
+
data += sent;
len -= sent;

@@ -138,7 +145,11 @@ static int domU_read_console(uint32_t vtermno, char *buf, int len)
cons = intf->in_cons;
prod = intf->in_prod;
mb(); /* get pointers before reading ring */
- BUG_ON((prod - cons) > sizeof(intf->in));
+
+ if ((prod - cons) > sizeof(intf->in)) {
+ pr_err_once("xencons: Illegal ring page indices");
+ return -EINVAL;
+ }

while (cons != prod && recv < len)
buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
--
2.26.2
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