bpf: Tighten tail call checks for lingering locks, RCU, preempt_disable

Browse source

[ Upstream commit 46f7ed32f7 ]

There are three situations when a program logically exits and transfers
control to the kernel or another program: bpf_throw, BPF_EXIT, and tail
calls. The former two check for any lingering locks and references, but
tail calls currently do not. Expand the checks to check for spin locks,
RCU read sections and preempt disabled sections.

Spin locks are indirectly preventing tail calls as function calls are
disallowed, but the checks for preemption and RCU are more relaxed,
hence ensure tail calls are prevented in their presence.

Fixes: 9bb00b2895 ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
Fixes: fc7566ad0a ("bpf: Introduce bpf_preempt_[disable,enable] kfuncs")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241103225940.1408302-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

This commit is contained in:

Kumar Kartikeya Dwivedi 2024-11-03 14:59:38 -08:00 • committed by Greg Kroah-Hartman

parent caf27ed9ea

commit aa51be3fa9

1 changed files with 15 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

15

kernel/bpf/verifier.c

View file