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scst: Port scst_readv() and scst_writev() to Linux kernel v5.10

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Additionally, prevent that these functions trigger memory allocation if
vlen > 8.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@9191 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2020-11-23 16:07:09 +00:00
parent e93e3cd2fb
commit a7214ad3d1
1 changed files with 40 additions and 47 deletions
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87
scst/src/scst_lib.c
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@@ -16,6 +16,7 @@
* GNU General Public License for more details.
*/
#include <linux/aio.h> /* struct kiocb for kernel v4.0 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/errno.h>
@@ -5987,6 +5988,7 @@ static void scst_complete_request_sense(struct scst_cmd *req_cmd)
return;
}
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 19, 0)
static int scst_cmp_fs_ds(void)
{
mm_segment_t fs = get_fs();
@@ -5994,6 +5996,7 @@ static int scst_cmp_fs_ds(void)
return memcmp(&fs, &ds, sizeof(fs));
}
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 9, 0) && !defined(RHEL_MAJOR)
ssize_t kernel_write(struct file *file, const void *buf, size_t count,
@@ -6012,38 +6015,35 @@ EXPORT_SYMBOL(kernel_write);
ssize_t scst_readv(struct file *file, const struct iovec *vec,
unsigned long vlen, loff_t *pos)
{
mm_segment_t old_fs = get_fs();
ssize_t result;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 14, 0)
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
struct iov_iter iter;
struct kiocb kiocb;
size_t count = 0;
int i;
set_fs(KERNEL_DS);
WARN_ON_ONCE(scst_cmp_fs_ds() != 0);
result = import_iovec(READ, (const struct iovec __force __user *)vec,
vlen, ARRAY_SIZE(iovstack), &iov, &iter);
if (result >= 0) {
result = vfs_iter_read(file, &iter, pos, 0);
BUG_ON(iov == iovstack);
kfree(iov);
}
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 6, 0) || \
(defined(CONFIG_SUSE_KERNEL) && \
LINUX_VERSION_CODE >= KERNEL_VERSION(4, 4, 0))
set_fs(KERNEL_DS);
WARN_ON_ONCE(scst_cmp_fs_ds() != 0);
result = vfs_readv(file, (const struct iovec __user *)vec, vlen, pos,
0);
BUILD_BUG_ON(sizeof(struct kvec) != sizeof(struct iovec));
BUILD_BUG_ON(offsetof(struct kvec, iov_base) !=
offsetof(struct iovec, iov_base));
BUILD_BUG_ON(offsetof(struct kvec, iov_len) !=
offsetof(struct iovec, iov_len));
init_sync_kiocb(&kiocb, file);
kiocb.ki_pos = *pos;
for (i = 0; i < vlen; i++)
count += vec[i].iov_len;
iov_iter_kvec(&iter, READ, (struct kvec *)vec, vlen, count);
result = call_read_iter(file, &kiocb, &iter);
sBUG_ON(result == -EIOCBQUEUED);
if (result > 0)
*pos += result;
#else
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
WARN_ON_ONCE(scst_cmp_fs_ds() != 0);
result = vfs_readv(file, (const struct iovec __user *)vec, vlen, pos);
#endif
set_fs(old_fs);
#endif
return result;
}
@@ -6062,38 +6062,31 @@ EXPORT_SYMBOL(scst_readv);
ssize_t scst_writev(struct file *file, const struct iovec *vec,
unsigned long vlen, loff_t *pos)
{
mm_segment_t old_fs = get_fs();
ssize_t result;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 14, 0)
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 19, 0)
struct iov_iter iter;
struct kiocb kiocb;
size_t count = 0;
int i;
set_fs(KERNEL_DS);
WARN_ON_ONCE(scst_cmp_fs_ds() != 0);
result = import_iovec(WRITE, (const struct iovec __force __user *)vec,
vlen, ARRAY_SIZE(iovstack), &iov, &iter);
if (result >= 0) {
file_start_write(file);
result = vfs_iter_write(file, &iter, pos, 0);
file_end_write(file);
BUG_ON(iov == iovstack);
kfree(iov);
}
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 6, 0) || \
(defined(CONFIG_SUSE_KERNEL) && \
LINUX_VERSION_CODE >= KERNEL_VERSION(4, 4, 0))
set_fs(KERNEL_DS);
WARN_ON_ONCE(scst_cmp_fs_ds() != 0);
result = vfs_writev(file, (const struct iovec __user *)vec, vlen, pos,
0);
init_sync_kiocb(&kiocb, file);
kiocb.ki_pos = *pos;
for (i = 0; i < vlen; i++)
count += vec[i].iov_len;
iov_iter_kvec(&iter, WRITE, (struct kvec *)vec, vlen, count);
file_start_write(file);
result = call_write_iter(file, &kiocb, &iter);
file_end_write(file);
sBUG_ON(result == -EIOCBQUEUED);
if (result > 0)
*pos += result;
#else
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
WARN_ON_ONCE(scst_cmp_fs_ds() != 0);
result = vfs_writev(file, (const struct iovec __user *)vec, vlen, pos);
#endif
set_fs(old_fs);
#endif
return result;
}