[PATCH -stable] uprobes: fix kernel info leak via "[uprobes]" vma

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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@xxxxxxxxxx/

Reported-by: Will Deacon <will@xxxxxxxxxx>
Fixes: d4b3b6384f98 ("uprobes/core: Allocate XOL slots for uprobes use")
Cc: stable@xxxxxxxxxxxxxxx
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
---
 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 50d7949be2b1..1650c05c9dc7 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1500,7 +1500,7 @@ 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;
-- 
2.25.1.362.g51ebf55


--OXfL5xGRrasGEqWY--





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