Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
sched_ext: Guard scx_dsq_move() against NULL kit->dsq after failed iter_new
bpf_iter_scx_dsq_new() clears kit->dsq on failure and
bpf_iter_scx_dsq_{next,destroy}() guard against that. scx_dsq_move() doesn't -
it dereferences kit->dsq immediately, so a BPF program that calls
scx_bpf_dsq_move[_vtime]() after a failed iter_new oopses the kernel.
Return false if kit->dsq is NULL.
Fixes: 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
+11
-1
+11
-1
kernel/sched/ext.c
+11
-1
kernel/sched/ext.c
···
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struct task_struct *p, u64 dsq_id, u64 enq_flags)
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{
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struct scx_dispatch_q *src_dsq = kit->dsq, *dst_dsq;
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-
struct scx_sched *sch = src_dsq->sched;
8079
+
struct scx_sched *sch;
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8080
struct rq *this_rq, *src_rq, *locked_rq;
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bool dispatched = false;
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bool in_balance;
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unsigned long flags;
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+
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+
/*
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+
* The verifier considers an iterator slot initialized on any
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+
* KF_ITER_NEW return, so a BPF program may legally reach here after
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+
* bpf_iter_scx_dsq_new() failed and left @kit->dsq NULL.
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+
*/
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+
if (unlikely(!src_dsq))
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+
return false;
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+
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+
sch = src_dsq->sched;
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if (!scx_vet_enq_flags(sch, dsq_id, &enq_flags))
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return false;