selftests/bpf: Check that JMP32 pointer vs zero jumps are not predictedgrafted

Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which
the verifier used to skip, contains an out of bounds map value access,
hence w/o the previous patch the program is accepted. See previous patch
for detailed description.

Reported-by: Nicholas Carlini <npc@anthropic.com>
Suggested-by: Nicholas Carlini <npc@anthropic.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/io_uring/memmap.h b/io_uring/memmap.h
new file mode 100644
index 000000000..f4cfbb6b9
--- /dev/null
+++ b/io_uring/memmap.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef IO_URING_MEMMAP_H
+#define IO_URING_MEMMAP_H
+
+#define IORING_MAP_OFF_PARAM_REGION		0x20000000ULL
+#define IORING_MAP_OFF_ZCRX_REGION		0x30000000ULL
+
+#define IORING_OFF_ZCRX_SHIFT		16
+
+struct page **io_pin_pages(unsigned long uaddr, unsigned long len, int *npages);
+
+#ifndef CONFIG_MMU
+unsigned int io_uring_nommu_mmap_capabilities(struct file *file);
+#endif
+unsigned long io_uring_get_unmapped_area(struct file *file, unsigned long addr,
+					 unsigned long len, unsigned long pgoff,
+					 unsigned long flags);
+int io_uring_mmap(struct file *file, struct vm_area_struct *vma);
+
+void io_free_region(struct user_struct *user, struct io_mapped_region *mr);
+int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr,
+		     struct io_uring_region_desc *reg,
+		     unsigned long mmap_offset);
+
+static inline void *io_region_get_ptr(struct io_mapped_region *mr)
+{
+	return mr->ptr;
+}
+
+static inline bool io_region_is_set(struct io_mapped_region *mr)
+{
+	return !!mr->nr_pages;
+}
+
+static inline void io_region_publish(struct io_ring_ctx *ctx,
+				     struct io_mapped_region *src_region,
+				     struct io_mapped_region *dst_region)
+{
+	/*
+	 * Once published mmap can find it without holding only the ->mmap_lock
+	 * and not ->uring_lock.
+	 */
+	guard(mutex)(&ctx->mmap_lock);
+	*dst_region = *src_region;
+}
+
+static inline size_t io_region_size(struct io_mapped_region *mr)
+{
+	return (size_t) mr->nr_pages << PAGE_SHIFT;
+}
+
+#endif