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io_uring/kbuf: sanitize peek buffer setup

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Harden the buffer peeking a bit, by adding a sanity check for it having
a valid size. Outside of that, arg->max_len is a size_t, though it's
only ever set to a 32-bit value (as it's governed by MAX_RW_COUNT).
Bump our needed check to a size_t so we know it fits. Finally, cap the
calculated needed iov value to the PEEK_MAX_IMPORT, which is the
maximum number of segments that should be peeked.

Fixes: 35c8711c8f ("io_uring/kbuf: add helpers for getting/peeking multiple buffers")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2024-08-20 18:31:58 -06:00
parent 1fc2ac428e
commit e0ee967630
1 changed files with 6 additions and 3 deletions
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9
io_uring/kbuf.c
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@ -218,10 +218,13 @@ static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg,
buf = io_ring_head_to_buf(br, head, bl->mask);
if (arg->max_len) {
int needed;
u32 len = READ_ONCE(buf->len);
size_t needed;
needed = (arg->max_len + buf->len - 1) / buf->len;
needed = min(needed, PEEK_MAX_IMPORT);
if (unlikely(!len))
return -ENOBUFS;
needed = (arg->max_len + len - 1) / len;
needed = min_not_zero(needed, (size_t) PEEK_MAX_IMPORT);
if (nr_avail > needed)
nr_avail = needed;
}