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authorChristoph Hellwig <hch@lst.de>2020-09-25 06:51:40 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2020-10-03 00:01:56 -0400
commitbfdc59701d6d100c99c3b987bcffd1c204e393c8 (patch)
treea88294580eba288886916d767713789aa06507f2 /mm
parentfb041b598997d63c0f7d7305dfae70046bf66fe1 (diff)
iov_iter: refactor rw_copy_check_uvector and import_iovec
Split rw_copy_check_uvector into two new helpers with more sensible calling conventions: - iovec_from_user copies a iovec from userspace either into the provided stack buffer if it fits, or allocates a new buffer for it. Returns the actually used iovec. It also verifies that iov_len does fit a signed type, and handles compat iovecs if the compat flag is set. - __import_iovec consolidates the native and compat versions of import_iovec. It calls iovec_from_user, then validates each iovec actually points to user addresses, and ensures the total length doesn't overflow. This has two major implications: - the access_process_vm case loses the total lenght checking, which wasn't required anyway, given that each call receives two iovecs for the local and remote side of the operation, and it verifies the total length on the local side already. - instead of a single loop there now are two loops over the iovecs. Given that the iovecs are cache hot this doesn't make a major difference Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'mm')
-rw-r--r--mm/process_vm_access.c34
1 files changed, 15 insertions, 19 deletions
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 29c052099aff..5e728c20c2be 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -276,20 +276,17 @@ static ssize_t process_vm_rw(pid_t pid,
if (rc < 0)
return rc;
if (!iov_iter_count(&iter))
- goto free_iovecs;
-
- rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
- iovstack_r, &iov_r);
- if (rc <= 0)
- goto free_iovecs;
-
+ goto free_iov_l;
+ iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r, false);
+ if (IS_ERR(iov_r)) {
+ rc = PTR_ERR(iov_r);
+ goto free_iov_l;
+ }
rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
-
-free_iovecs:
if (iov_r != iovstack_r)
kfree(iov_r);
+free_iov_l:
kfree(iov_l);
-
return rc;
}
@@ -333,18 +330,17 @@ compat_process_vm_rw(compat_pid_t pid,
if (rc < 0)
return rc;
if (!iov_iter_count(&iter))
- goto free_iovecs;
- rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
- UIO_FASTIOV, iovstack_r,
- &iov_r);
- if (rc <= 0)
- goto free_iovecs;
-
+ goto free_iov_l;
+ iov_r = iovec_from_user((const struct iovec __user *)rvec, riovcnt,
+ UIO_FASTIOV, iovstack_r, true);
+ if (IS_ERR(iov_r)) {
+ rc = PTR_ERR(iov_r);
+ goto free_iov_l;
+ }
rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
-
-free_iovecs:
if (iov_r != iovstack_r)
kfree(iov_r);
+free_iov_l:
kfree(iov_l);
return rc;
}