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From: Jan Beulich <jbeulich@suse.com>
To: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	Ian Jackson <iwj@xenproject.org>, Julien Grall <julien@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>
Subject: [PATCH 9/9] gnttab: don't silently truncate GFNs in compat setup-table handling
Date: Thu, 26 Aug 2021 12:15:10 +0200	[thread overview]
Message-ID: <c3f4d5ce-6ac8-1d1c-eed0-704354f8a5f7@suse.com> (raw)
In-Reply-To: <eb7bbd51-1da3-9a7f-27c7-49dea1a41488@suse.com>

Returning back truncated frame numbers is unhelpful: Quite likely
they're not owned by the domain (if it's PV), or we may misguide the
guest into writing grant entries into a page that it actually uses for
other purposes.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
RFC: Arguably in the 32-bit PV case it may be necessary to instead put
     in place an explicit address restriction when allocating
     ->shared_raw[N]. This is currently implicit by alloc_xenheap_page()
     only returning memory covered by the direct-map.

--- a/xen/common/compat/grant_table.c
+++ b/xen/common/compat/grant_table.c
@@ -175,8 +175,15 @@ int compat_grant_table_op(unsigned int c
                                  i < (_s_)->nr_frames; ++i ) \
                     { \
                         compat_pfn_t frame = (_s_)->frame_list.p[i]; \
-                        if ( __copy_to_compat_offset((_d_)->frame_list, \
-                                                     i, &frame, 1) ) \
+                        if ( frame != (_s_)->frame_list.p[i] ) \
+                        { \
+                            if ( VALID_M2P((_s_)->frame_list.p[i]) ) \
+                                (_s_)->status = GNTST_address_too_big; \
+                            else \
+                                frame |= 0x80000000U;\
+                        } \
+                        else if ( __copy_to_compat_offset((_d_)->frame_list, \
+                                                          i, &frame, 1) ) \
                             (_s_)->status = GNTST_bad_virt_addr; \
                     } \
                 } while (0)



  parent reply	other threads:[~2021-08-26 10:15 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26 10:06 [PATCH 0/9] gnttab: further work from XSA-380 / -382 context Jan Beulich
2021-08-26 10:09 ` [PATCH 1/9] gnttab: defer allocation of maptrack frames table Jan Beulich
2021-09-06 13:13   ` Julien Grall
2021-09-06 13:29     ` Jan Beulich
2021-09-06 13:33       ` Julien Grall
2021-09-06 13:58         ` Jan Beulich
2021-09-06 14:05   ` Andrew Cooper
2021-09-06 14:43     ` Jan Beulich
2021-08-26 10:11 ` [PATCH 2/9] gnttab: drop a redundant expression from gnttab_release_mappings() Jan Beulich
2021-09-06 13:15   ` Julien Grall
2021-08-26 10:12 ` [PATCH 3/9] gnttab: fold recurring is_iomem_page() Jan Beulich
2021-09-06 13:35   ` Julien Grall
2021-09-06 14:02     ` Jan Beulich
2021-08-26 10:13 ` [PATCH 4/9] gnttab: drop GNTMAP_can_fail Jan Beulich
2021-08-26 11:45   ` Andrew Cooper
2021-08-26 13:03     ` Jan Beulich
2021-08-26 13:13       ` Andrew Cooper
2021-08-26 10:13 ` [PATCH 5/9] gnttab: defer allocation of status frame tracking array Jan Beulich
2021-08-26 10:13 ` [PATCH 6/9] gnttab: check handle early in gnttab_get_status_frames() Jan Beulich
2021-09-06 13:41   ` Julien Grall
2021-08-26 10:14 ` [PATCH 7/9] gnttab: no need to translate handle for gnttab_get_status_frames() Jan Beulich
2022-10-07 18:24   ` Andrew Cooper
2021-08-26 10:14 ` [PATCH 8/9] gnttab: bail from GFN-storing loops early in case of error Jan Beulich
2022-10-07 19:36   ` Andrew Cooper
2022-10-10  9:30     ` Jan Beulich
2021-08-26 10:15 ` Jan Beulich [this message]
2022-10-07 19:57   ` [PATCH 9/9] gnttab: don't silently truncate GFNs in compat setup-table handling Andrew Cooper
2022-10-10  8:46     ` Jan Beulich
2022-01-05  7:42 ` Ping: [PATCH 0/9] gnttab: further work from XSA-380 / -382 context Jan Beulich
2022-10-07 13:49 ` Jan Beulich
2022-10-07 18:09   ` Andrew Cooper

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