commit: e3756477aec028427fec767957c0d4b6cfb87208 From: Jeff Mahoney <[email protected]> Date: Fri, 10 Aug 2012 15:07:09 -0400 Subject: printk: Fix calculation of length used to discard records
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. CC: [email protected] Signed-off-by: Jeff Mahoney <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> --- kernel/printk.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/kernel/printk.c b/kernel/printk.c index 6a76ab9..66a2ea3 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -1034,6 +1034,7 @@ 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++; } @@ -1046,6 +1047,7 @@ 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++; } -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
