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| author | Jeff Mahoney <jeffm@suse.com> | 2012-08-10 15:07:09 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-08-15 07:53:03 -0700 |
| commit | 6fd9636dc32ee59c03434a3c6044b41621d806e8 (patch) | |
| tree | 98d9a080dc90517d0345b965a058e1914a2adf0f | |
| parent | 9b9efe7459c14ccb49e87f1bc46289a9a26e8602 (diff) | |
| download | lwn-6fd9636dc32ee59c03434a3c6044b41621d806e8.tar.gz lwn-6fd9636dc32ee59c03434a3c6044b41621d806e8.zip | |
printk: Fix calculation of length used to discard records
commit e3756477aec028427fec767957c0d4b6cfb87208 upstream.
While tracking down a weird buffer overflow issue in a program that
looked to be sane, I started double checking the length returned by
syslog(SYSLOG_ACTION_READ_ALL, ...) to make sure it wasn't overflowing
the buffer.
Sure enough, it was. I saw this in strace:
11339 syslog(SYSLOG_ACTION_READ_ALL, "<5>[244017.708129] REISERFS (dev"..., 8192) = 8279
It turns out that the loops that calculate how much space the entries
will take when they're copied don't include the newlines and prefixes
that will be included in the final output since prev flags is passed as
zero.
This patch properly accounts for it and fixes the overflow.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/printk.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 21bea76a9fff..146827f81a06 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -999,6 +999,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear) struct log *msg = log_from_idx(idx); len += msg_print_text(msg, prev, true, NULL, 0); + prev = msg->flags; idx = log_next(idx); seq++; } @@ -1011,6 +1012,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear) struct log *msg = log_from_idx(idx); len -= msg_print_text(msg, prev, true, NULL, 0); + prev = msg->flags; idx = log_next(idx); seq++; } |