On Fri, Sep 9, 2022 at 7:07 PM <eadavis@xxxxxxxx> wrote: > > From: eadivs <eadivs@xxxxxxxx> > > syzbot is reporting WARNING: ODEBUG bug in htab_map_alloc(), the > loop exits without reaching length HASHTAB_MAP_LOCK_COUNT, and > the loop continues HASHTAB_MAP_LOCK_COUNT times in label > free_map_locked. Please use [PATCH bpf] vs [PATCH bpf-next] in subject to indicate which tree you're targeting. Also, it seems your email hasn't reached the mailing list for some reason. Are you sure that the issue is due to HASHTAB_MAP_LOCK_COUNT? The code seems fine as is; unconditionally calling free on NULL shouldn't be an issue. htab_map_alloc+0xc76/0x1620 kernel/bpf/hashtab.c:632 Which, if I'm looking at the function is: bpf_map_area_free(htab); ? > Link: https://syzkaller.appspot.com/bug?extid=5d1da78b375c3b5e6c2b > Reported-by: syzbot+5d1da78b375c3b5e6c2b@xxxxxxxxxxxxxxxxxxxxxxxxx > Signed-off-by: eadivs <eadivs@xxxxxxxx> > --- > kernel/bpf/hashtab.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c > index 65877967f414..f5381e1c00a6 100644 > --- a/kernel/bpf/hashtab.c > +++ b/kernel/bpf/hashtab.c > @@ -473,7 +473,7 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) > bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU); > bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC); > struct bpf_htab *htab; > - int err, i; > + int err, i, j = HASHTAB_MAP_LOCK_COUNT; > > htab = kzalloc(sizeof(*htab), GFP_USER | __GFP_ACCOUNT); > if (!htab) > @@ -523,8 +523,10 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) > sizeof(int), > sizeof(int), > GFP_USER); > - if (!htab->map_locked[i]) > + if (!htab->map_locked[i]) { > + j = i; > goto free_map_locked; > + } > } > > if (htab->map.map_flags & BPF_F_ZERO_SEED) > @@ -554,7 +556,7 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) > free_prealloc: > prealloc_destroy(htab); > free_map_locked: > - for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++) > + for (i = 0; i < j; i++) > free_percpu(htab->map_locked[i]); > bpf_map_area_free(htab->buckets); > free_htab: > -- > 2.37.2 >
