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charset="utf-8" #syz test diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 3615c06b7dfa..c0ee51db8eed 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -42,6 +42,28 @@ static inline int stack_map_data_size(struct bpf_map *ma= p) sizeof(struct bpf_stack_build_id) : sizeof(u64); } +/** + * stack_map_calculate_max_depth - Calculate maximum allowed stack trace d= epth + * @size: Size of the buffer/map value in bytes + * @elem_size: Size of each stack trace element + * @flags: BPF stack trace flags (BPF_F_USER_STACK, BPF_F_USER_BUILD_ID, = ...) + * + * Return: Maximum number of stack trace entries that can be safely stored + */ +static u32 stack_map_calculate_max_depth(u32 size, u32 elem_size, u64 flag= s) +{ + u32 skip =3D flags & BPF_F_SKIP_FIELD_MASK; + u32 max_depth; + u32 curr_sysctl_max_stack =3D READ_ONCE(sysctl_perf_event_max_stack= ); + + max_depth =3D size / elem_size; + max_depth +=3D skip; + if (max_depth > curr_sysctl_max_stack) + return curr_sysctl_max_stack; + + return max_depth; +} + static int prealloc_elems_and_freelist(struct bpf_stack_map *smap) { u64 elem_size =3D sizeof(struct stack_map_bucket) + @@ -251,8 +273,8 @@ static long __bpf_get_stackid(struct bpf_map *map, { struct bpf_stack_map *smap =3D container_of(map, struct bpf_stack_m= ap, map); struct stack_map_bucket *bucket, *new_bucket, *old_bucket; + u32 hash, id, trace_nr, trace_len, i, max_depth; u32 skip =3D flags & BPF_F_SKIP_FIELD_MASK; - u32 hash, id, trace_nr, trace_len, i; bool user =3D flags & BPF_F_USER_STACK; u64 *ips; bool hash_matches; @@ -261,7 +283,8 @@ static long __bpf_get_stackid(struct bpf_map *map, /* skipping more than usable stack trace */ return -EFAULT; - trace_nr =3D trace->nr - skip; + max_depth =3D stack_map_calculate_max_depth(map->value_size, stack_= map_data_size(map), flags); + trace_nr =3D min_t(u32, trace->nr - skip, max_depth - skip); trace_len =3D trace_nr * sizeof(u64); ips =3D trace->ip + skip; hash =3D jhash2((u32 *)ips, trace_len / sizeof(u32), 0); @@ -300,20 +323,17 @@ static long __bpf_get_stackid(struct bpf_map *map, BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, u64, flags) { - u32 max_depth =3D map->value_size / stack_map_data_size(map); - u32 skip =3D flags & BPF_F_SKIP_FIELD_MASK; + u32 elem_size =3D stack_map_data_size(map); bool user =3D flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; bool kernel =3D !user; + u32 max_depth; if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL; - max_depth +=3D skip; - if (max_depth > sysctl_perf_event_max_stack) - max_depth =3D sysctl_perf_event_max_stack; - + max_depth =3D stack_map_calculate_max_depth(map->value_size, elem_s= ize, flags); trace =3D get_perf_callchain(regs, 0, kernel, user, max_depth, false, false); @@ -390,15 +410,11 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_= data_kern *, ctx, return -EFAULT; nr_kernel =3D count_kernel_ip(trace); + __u64 nr =3D trace->nr; /* save original */ if (kernel) { - __u64 nr =3D trace->nr; - trace->nr =3D nr_kernel; ret =3D __bpf_get_stackid(map, trace, flags); - - /* restore nr */ - trace->nr =3D nr; } else { /* user */ u64 skip =3D flags & BPF_F_SKIP_FIELD_MASK; @@ -409,6 +425,10 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_d= ata_kern *, ctx, flags =3D (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; ret =3D __bpf_get_stackid(map, trace, flags); } + + /* restore nr */ + trace->nr =3D nr; + return ret; } @@ -426,7 +446,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struc= t task_struct *task, struct perf_callchain_entry *trace_in, void *buf, u32 size, u64 flags, bool may_fault) { - u32 trace_nr, copy_len, elem_size, num_elem, max_depth; + u32 trace_nr, copy_len, elem_size, max_depth; bool user_build_id =3D flags & BPF_F_USER_BUILD_ID; bool crosstask =3D task && task !=3D current; u32 skip =3D flags & BPF_F_SKIP_FIELD_MASK; @@ -458,21 +478,20 @@ static long __bpf_get_stack(struct pt_regs *regs, str= uct task_struct *task, goto clear; } - num_elem =3D size / elem_size; - max_depth =3D num_elem + skip; - if (sysctl_perf_event_max_stack < max_depth) - max_depth =3D sysctl_perf_event_max_stack; + max_depth =3D stack_map_calculate_max_depth(size, elem_size, flags); if (may_fault) rcu_read_lock(); /* need RCU for perf's callchain below */ - if (trace_in) + if (trace_in) { trace =3D trace_in; - else if (kernel && task) + trace->nr =3D min_t(u32, trace->nr, max_depth); + } else if (kernel && task) { trace =3D get_callchain_entry_for_task(task, max_depth); - else + } else { trace =3D get_perf_callchain(regs, 0, kernel, user, max_dep= th, crosstask, false); + } if (unlikely(!trace) || trace->nr < skip) { if (may_fault) @@ -481,7 +500,6 @@ static long __bpf_get_stack(struct pt_regs *regs, struc= t task_struct *task, } trace_nr =3D trace->nr - skip; - trace_nr =3D (trace_nr <=3D num_elem) ? trace_nr : num_elem; copy_len =3D trace_nr * elem_size; ips =3D trace->ip + skip; -- 2.47.3