From: Kuniyuki Iwashima kuniyu@amazon.com
[ Upstream commit 0947ae1121083d363d522ff7518ee72b55bd8d29 ]
While reading bpf_jit_limit, it can be changed concurrently via sysctl, WRITE_ONCE() in __do_proc_doulongvec_minmax(). The size of bpf_jit_limit is long, so we need to add a paired READ_ONCE() to avoid load-tearing.
Fixes: ede95a63b5e8 ("bpf: add bpf_jit_limit knob to restrict unpriv allocations") Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/20220823215804.2177-1-kuniyu@amazon.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index fb6bd57228a84..cf44ff50b1f23 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1005,7 +1005,7 @@ pure_initcall(bpf_jit_charge_init);
int bpf_jit_charge_modmem(u32 size) { - if (atomic_long_add_return(size, &bpf_jit_current) > bpf_jit_limit) { + if (atomic_long_add_return(size, &bpf_jit_current) > READ_ONCE(bpf_jit_limit)) { if (!bpf_capable()) { atomic_long_sub(size, &bpf_jit_current); return -EPERM;