6.13-stable review patch. If anyone has any objections, please let me know.
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From: Alan Maguire alan.maguire@oracle.com
[ Upstream commit 517e8a7835e8cfb398a0aeb0133de50e31cae32b ]
On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y, arena_htab tests cause a segmentation fault and soft lockup. The same failure is not observed with 4k pages on aarch64.
It turns out arena_map_free() is calling apply_to_existing_page_range() with the address returned by bpf_arena_get_kern_vm_start(). If this address is not page-aligned the code ends up calling apply_to_pte_range() with that unaligned address causing soft lockup.
Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the division by 2 in bpf_arena_get_kern_vm_start() returns a page-aligned value.
Fixes: 317460317a02 ("bpf: Introduce bpf_arena.") Reported-by: Colm Harrington colm.harrington@oracle.com Suggested-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Alan Maguire alan.maguire@oracle.com Link: https://lore.kernel.org/r/20250205170059.427458-1-alan.maguire@oracle.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/arena.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c index 8caf56a308d96..eac5d1edefe97 100644 --- a/kernel/bpf/arena.c +++ b/kernel/bpf/arena.c @@ -39,7 +39,7 @@ */
/* number of bytes addressable by LDX/STX insn with 16-bit 'off' field */ -#define GUARD_SZ (1ull << sizeof_field(struct bpf_insn, off) * 8) +#define GUARD_SZ round_up(1ull << sizeof_field(struct bpf_insn, off) * 8, PAGE_SIZE << 1) #define KERN_VM_SZ (SZ_4G + GUARD_SZ)
struct bpf_arena {