linux.git/drivers/xen/gntalloc.c, branch v7.2-rc2

xen/gntalloc: validate grant count before allocation

2026-07-01T07:58:24+00:00

gntalloc_ioctl_alloc() allocates the grant-id array before checking
whether the requested count fits within the global grant limit. Counts
above that limit cannot succeed, so reject them before the
user-controlled allocation reaches kcalloc().

Use a subtraction-based check while holding gref_mutex so adding the
requested count cannot wrap. Also cast the count before advancing the
per-file index so the page-size multiplication is performed in 64-bit
arithmetic.

Signed-off-by: Yousef Alhouseen 
Reviewed-by: Juergen Gross 
Signed-off-by: Juergen Gross 
Message-ID: <20260626223805.43781-3-alhouseenyousef@gmail.com>

xen/gntalloc: make grant counters unsigned

2026-07-01T07:58:24+00:00

The module limit and current allocation count cannot validly be
negative. Give both variables unsigned types so their representation
matches the u32 grant count supplied through the ioctl and negative
module parameter values are rejected by parameter parsing.

This also prepares the limit check for overflow-safe unsigned
arithmetic.

Signed-off-by: Yousef Alhouseen 
Reviewed-by: Juergen Gross 
Signed-off-by: Juergen Gross 
Message-ID: <20260626223805.43781-2-alhouseenyousef@gmail.com>

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using

    git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook

xen/gntalloc: Replace UAPI 1-element array

2024-02-13T08:06:48+00:00

Without changing the structure size (since it is UAPI), add a proper
flexible array member, and reference it in the kernel so that it will
not be trip the array-bounds sanitizer[1].

Link: https://github.com/KSPP/linux/issues/113 [1]
Cc: Juergen Gross 
Cc: Stefano Stabellini 
Cc: Oleksandr Tyshchenko 
Cc: Gustavo A. R. Silva 
Cc: xen-devel@lists.xenproject.org
Signed-off-by: Kees Cook 
Reviewed-by: Gustavo A. R. Silva 
Link: https://lore.kernel.org/r/20240206170320.work.437-kees@kernel.org
Signed-off-by: Juergen Gross

mm: replace vma->vm_flags direct modifications with modifier calls

2023-02-10T00:51:39+00:00

Replace direct modifications to vma->vm_flags with calls to modifier
functions to be able to track flag changes and to keep vma locking
correctness.

[akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo]
Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Acked-by: Michal Hocko 
Acked-by: Mel Gorman 
Acked-by: Mike Rapoport (IBM) 
Acked-by: Sebastian Reichel 
Reviewed-by: Liam R. Howlett 
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Andy Lutomirski 
Cc: Arjun Roy 
Cc: Axel Rasmussen 
Cc: David Hildenbrand 
Cc: David Howells 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Eric Dumazet 
Cc: Greg Thelen 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Jann Horn 
Cc: Joel Fernandes 
Cc: Johannes Weiner 
Cc: Kent Overstreet 
Cc: Laurent Dufour 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox 
Cc: Minchan Kim 
Cc: Paul E. McKenney 
Cc: Peter Oskolkov 
Cc: Peter Xu 
Cc: Peter Zijlstra 
Cc: Punit Agrawal 
Cc: Sebastian Andrzej Siewior 
Cc: Shakeel Butt 
Cc: Soheil Hassas Yeganeh 
Cc: Song Liu 
Cc: Vlastimil Babka 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

xen: switch gnttab_end_foreign_access() to take a struct page pointer

2022-05-27T09:05:29+00:00

Instead of a virtual kernel address use a pointer of the associated
struct page as second parameter of gnttab_end_foreign_access().

Most users have that pointer available already and are creating the
virtual address from it, risking problems in case the memory is
located in highmem.

gnttab_end_foreign_access() itself won't need to get the struct page
from the address again.

Suggested-by: Jan Beulich 
Signed-off-by: Juergen Gross 
Reviewed-by: Jan Beulich 
Signed-off-by: Juergen Gross

xen: Convert kmap() to kmap_local_page()

2022-04-20T20:22:18+00:00

kmap() is being deprecated and these usages are all local to the thread
so there is no reason kmap_local_page() can't be used.

Replace kmap() calls with kmap_local_page().

Signed-off-by: Alaa Mohamed 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/20220419234328.10346-1-eng.alaamohamedsoliman.am@gmail.com
Signed-off-by: Boris Ostrovsky

xen/grant-table: remove readonly parameter from functions

2022-03-16T01:34:40+00:00

The gnttab_end_foreign_access() family of functions is taking a
"readonly" parameter, which isn't used. Remove it from the function
parameters.

Signed-off-by: Juergen Gross 
Link: https://lore.kernel.org/r/20220311103429.12845-3-jgross@suse.com
Reviewed-by: Jan Beulich 
Acked-by: Christian Schoenebeck 
Signed-off-by: Boris Ostrovsky

xen/gntalloc: don't use gnttab_query_foreign_access()

2022-03-07T08:48:54+00:00

Using gnttab_query_foreign_access() is unsafe, as it is racy by design.

The use case in the gntalloc driver is not needed at all. While at it
replace the call of gnttab_end_foreign_access_ref() with a call of
gnttab_end_foreign_access(), which is what is really wanted there. In
case the grant wasn't used due to an allocation failure, just free the
grant via gnttab_free_grant_reference().

This is CVE-2022-23039 / part of XSA-396.

Reported-by: Demi Marie Obenour 
Signed-off-by: Juergen Gross 
Reviewed-by: Jan Beulich 
---
V3:
- fix __del_gref() (Jan Beulich)