From: Juergen Gross Date: Wed, 22 Apr 2020 13:07:53 +0000 (+0200) Subject: xen/grants: fix hypercall continuation for GNTTABOP_cache_flush X-Git-Tag: archive/raspbian/4.14.0+80-gd101b417b7-1+rpi1^2~63^2~330 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=46d8f69d466a05863737fb81d8c9ef39c3be8b45;p=xen.git xen/grants: fix hypercall continuation for GNTTABOP_cache_flush The GNTTABOP_cache_flush hypercall has a wrong test for hypercall continuation, the test today is: if ( rc > 0 || opaque_out != 0 ) Unfortunately this will be true even in case of an error (rc < 0), possibly leading to very long lasting hypercalls (times of more than an hour have been observed in a test case). Correct the test condition to result in false with rc < 0 and set opaque_out only if no error occurred, to be on the safe side. Partially-suggested-by: Jan Beulich Signed-off-by: Juergen Gross Reviewed-by: Julien Grall Reviewed-by: Stefano Stabellini --- diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c index 96080b3dec..5ef7ff940d 100644 --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -3626,12 +3626,12 @@ do_grant_table_op( if ( unlikely(!guest_handle_okay(cflush, count)) ) goto out; rc = gnttab_cache_flush(cflush, &opaque_in, count); - if ( rc > 0 ) + if ( rc >= 0 ) { guest_handle_add_offset(cflush, rc); uop = guest_handle_cast(cflush, void); + opaque_out = opaque_in; } - opaque_out = opaque_in; break; } @@ -3641,7 +3641,7 @@ do_grant_table_op( } out: - if ( rc > 0 || opaque_out != 0 ) + if ( rc > 0 || (opaque_out != 0 && rc == 0) ) { /* Adjust rc, see gnttab_copy() for why this is needed. */ if ( cmd == GNTTABOP_copy )