4.19-stable review patch. If anyone has any objections, please let me know.
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From: Oleg Nesterov oleg@redhat.com
commit 34820304cc2cd1804ee1f8f3504ec77813d29c8e upstream.
xol_add_vma() maps the uninitialized page allocated by __create_xol_area() into userspace. On some architectures (x86) this memory is readable even without VM_READ, VM_EXEC results in the same pgprot_t as VM_EXEC|VM_READ, although this doesn't really matter, debugger can read this memory anyway.
Link: https://lore.kernel.org/all/20240929162047.GA12611@redhat.com/
Reported-by: Will Deacon will@kernel.org Fixes: d4b3b6384f98 ("uprobes/core: Allocate XOL slots for uprobes use") Cc: stable@vger.kernel.org Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Oleg Nesterov oleg@redhat.com Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/events/uprobes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 3361da45e1db7..3ca91daddc9f5 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1198,7 +1198,7 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
area->xol_mapping.name = "[uprobes]"; area->xol_mapping.pages = area->pages; - area->pages[0] = alloc_page(GFP_HIGHUSER); + area->pages[0] = alloc_page(GFP_HIGHUSER | __GFP_ZERO); if (!area->pages[0]) goto free_bitmap; area->pages[1] = NULL;