[PATCH 0/8] Rework KERN_<LEVEL>
From: akpm@linux-foundation.org (Andrew Morton)
Date: 2012-06-05 23:09:37
Also in:
alsa-devel, linux-btrfs, lkml
On Wed, 06 Jun 2012 00:55:00 +0200 Kay Sievers [off-list ref] wrote:
quoted hunk ↗ jump to hunk
On Tue, 2012-06-05 at 14:28 -0700, Andrew Morton wrote:quoted
devkmsg_writev() does weird and wonderful things with facilities/levels. That function incorrectly returns "success" when copy_from_user() faults, btw.Oh. Better? Thanks, Kay From: Kay Sievers <redacted> Subject: kmsg: /dev/kmsg - properly return possible copy_from_user() failure Reported-By: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Kay Sievers <kay@vrfy.org --- printk.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)diff --git a/kernel/printk.c b/kernel/printk.c index 32462d2..6bdacab 100644 --- a/kernel/printk.c +++ b/kernel/printk.c@@ -365,8 +365,10 @@ static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv, line = buf; for (i = 0; i < count; i++) { - if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) + if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) { + ret = -EFAULT; goto out; + } line += iv[i].iov_len; }
Strictly speaking, when write() encounters an error it should return number-of-bytes-written, or an errno if it wrote zero bytes. So something like
--- a/kernel/printk.c~a
+++ a/kernel/printk.c@@ -355,7 +355,7 @@ static ssize_t devkmsg_writev(struct kio int level = default_message_loglevel; int facility = 1; /* LOG_USER */ size_t len = iov_length(iv, count); - ssize_t ret = len; + ssize_t ret; if (len > LOG_LINE_MAX) return -EINVAL;
@@ -365,8 +365,12 @@ static ssize_t devkmsg_writev(struct kio line = buf; for (i = 0; i < count; i++) { - if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) + if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) { + ret = line - buf; + if (!ret) + ret = -EFAULT; goto out; + } line += iv[i].iov_len; }
@@ -396,6 +400,7 @@ static ssize_t devkmsg_writev(struct kio line[len] = '\0'; printk_emit(facility, level, NULL, 0, "%s", line); + ret = 0; out: kfree(buf); return ret;
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