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pstore: simplify write_user_compat()

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Nothing actually uses write_user_compat() currently, but there is no
reason to reuse the dmesg buffer. Instead, just allocate a new record
buffer, copy in from userspace, and pass it to write() as normal.

Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2017-03-07 13:57:11 -08:00
parent 4c9ec21976
commit 30800d9977
1 changed files with 18 additions and 24 deletions
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42
fs/pstore/platform.c
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@ -635,33 +635,27 @@ static void pstore_unregister_console(void) {}
static int pstore_write_user_compat(struct pstore_record *record,
const char __user *buf)
{
unsigned long flags = 0;
size_t i, bufsize, total_size = record->size;
long ret = 0;
int ret = 0;
if (unlikely(!access_ok(VERIFY_READ, buf, total_size)))
return -EFAULT;
bufsize = total_size;
if (bufsize > psinfo->bufsize)
bufsize = psinfo->bufsize;
record->buf = psinfo->buf;
spin_lock_irqsave(&psinfo->buf_lock, flags);
for (i = 0; i < total_size; ) {
size_t c = min(total_size - i, bufsize);
if (record->buf)
return -EINVAL;
ret = __copy_from_user(record->buf, buf + i, c);
if (unlikely(ret != 0)) {
ret = -EFAULT;
break;
}
record->size = c;
ret = record->psi->write(record);
if (unlikely(ret < 0))
break;
i += c;
record->buf = kmalloc(record->size, GFP_KERNEL);
if (!record->buf)
return -ENOMEM;
if (unlikely(copy_from_user(record->buf, buf, record->size))) {
ret = -EFAULT;
goto out;
}
spin_unlock_irqrestore(&psinfo->buf_lock, flags);
return unlikely(ret < 0) ? ret : total_size;
ret = record->psi->write(record);
out:
kfree(record->buf);
record->buf = NULL;
return unlikely(ret < 0) ? ret : record->size;
}
/*