crypto_get_ptrs() should always write to *out_data_2

Callers will check if it has been set to NULL before trying to access
it, but never initialize it themselves. Whenever "one block spans two
iovecs", `crypto_get_ptrs()` will return, without ever setting
`*out_data_2 = NULL`. The caller will then do a NULL check against the
uninitailized pointer and if it is not zero, pass it to `memcpy()`.

The only reason this has not caused horrible runtime issues is because
`memcpy()` should be told to copy zero bytes when this happens. That
said, this is technically undefined behavior, so we should correct it so
that future changes to the code cannot trigger it.

Clang's static analyzer found this with the help of CodeChecker's CTU
analysis.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14043
This commit is contained in:
Richard Yao 2022-10-15 23:35:56 -04:00 committed by Brian Behlendorf
parent 44f71818f8
commit c77d2d7415

View File

@ -106,8 +106,10 @@ crypto_get_ptrs(crypto_data_t *out, void **iov_or_mp, offset_t *current_offset,
} else {
/* one block spans two iovecs */
*out_data_1_len = iov_len - offset;
if (vec_idx == zfs_uio_iovcnt(uio))
if (vec_idx == zfs_uio_iovcnt(uio)) {
*out_data_2 = NULL;
return;
}
vec_idx++;
zfs_uio_iov_at_index(uio, vec_idx, &iov_base, &iov_len);
*out_data_2 = (uint8_t *)iov_base;