From 03f6f038c4d6d639e14c0e5a3e2bb34e0339ee06 Mon Sep 17 00:00:00 2001 From: Tao Ma Date: Thu, 7 Jul 2011 13:39:00 +0100 Subject: [PATCH] ext4: init timer earlier to avoid a kernel panic in __save_error_info, CVE-2011-2493 During mount, when we fail to open journal inode or root inode, the __save_error_info will mod_timer. But actually s_err_report isn't initialized yet and the kernel oops. The detailed information can be found https://bugzilla.kernel.org/show_bug.cgi?id=32082. The best way is to check whether the timer s_err_report is initialized or not. But it seems that in include/linux/timer.h, we can't find a good function to check the status of this timer, so this patch just move the initializtion of s_err_report earlier so that we can avoid the kernel panic. The corresponding del_timer is also added in the error path. Reported-by: Sami Liedes Signed-off-by: Tao Ma Signed-off-by: "Theodore Ts'o" (cherry picked from commit 0449641130f5652b344ef6fa39fa019d7e94660a) CVE-2011-2493 BugLink: http://bugs.launchpad.net/bugs/806929 Signed-off-by: Andy Whitcroft Signed-off-by: Tim Gardner --- fs/ext4/super.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 9bada49..59e567e 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3377,6 +3377,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) get_random_bytes(&sbi->s_next_generation, sizeof(u32)); spin_lock_init(&sbi->s_next_gen_lock); + init_timer(&sbi->s_err_report); + sbi->s_err_report.function = print_daily_error_info; + sbi->s_err_report.data = (unsigned long) sb; + err = percpu_counter_init(&sbi->s_freeblocks_counter, ext4_count_free_blocks(sb)); if (!err) { @@ -3632,9 +3636,6 @@ no_journal: "Opts: %s%s%s", descr, sbi->s_es->s_mount_opts, *sbi->s_es->s_mount_opts ? "; " : "", orig_data); - init_timer(&sbi->s_err_report); - sbi->s_err_report.function = print_daily_error_info; - sbi->s_err_report.data = (unsigned long) sb; if (es->s_error_count) mod_timer(&sbi->s_err_report, jiffies + 300*HZ); /* 5 minutes */ @@ -3656,6 +3657,7 @@ failed_mount_wq: sbi->s_journal = NULL; } failed_mount3: + del_timer(&sbi->s_err_report); if (sbi->s_flex_groups) { if (is_vmalloc_addr(sbi->s_flex_groups)) vfree(sbi->s_flex_groups); -- 1.7.10.4