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io_uring/rsrc: ensure segments counts are correct on kbuf buffers

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kbuf imports have the front offset adjusted and segments removed, but
the tail segments are still included in the segment count that gets
passed in the iov_iter. As the segments aren't necessarily all the
same size, move importing to a separate helper and iterate the
mapped length to get an exact count.

Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2025-04-16 16:48:26 -06:00
parent 80c7378f94
commit b419bed4f0
1 changed files with 22 additions and 5 deletions
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27
io_uring/rsrc.c
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@ -1032,6 +1032,26 @@ static int validate_fixed_range(u64 buf_addr, size_t len,
return 0;
}
static int io_import_kbuf(int ddir, struct iov_iter *iter,
struct io_mapped_ubuf *imu, size_t len, size_t offset)
{
size_t count = len + offset;
iov_iter_bvec(iter, ddir, imu->bvec, imu->nr_bvecs, count);
iov_iter_advance(iter, offset);
if (count < imu->len) {
const struct bio_vec *bvec = iter->bvec;
while (len > bvec->bv_len) {
len -= bvec->bv_len;
bvec++;
}
iter->nr_segs = 1 + bvec - iter->bvec;
}
return 0;
}
static int io_import_fixed(int ddir, struct iov_iter *iter,
struct io_mapped_ubuf *imu,
u64 buf_addr, size_t len)
@ -1052,11 +1072,8 @@ static int io_import_fixed(int ddir, struct iov_iter *iter,
offset = buf_addr - imu->ubuf;
if (imu->is_kbuf) {
iov_iter_bvec(iter, ddir, imu->bvec, imu->nr_bvecs, offset + len);
iov_iter_advance(iter, offset);
return 0;
}
if (imu->is_kbuf)
return io_import_kbuf(ddir, iter, imu, len, offset);
/*
* Don't use iov_iter_advance() here, as it's really slow for