The patch titled Subject: sysctl: protect poll() in entries that may go away has been removed from the -mm tree. Its filename was sysctl-protect-poll-in-entries-that-may-go-away.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Lucas De Marchi <lucas.demarchi@xxxxxxxxxxxxxx> Subject: sysctl: protect poll() in entries that may go away Protect code accessing ctl_table by grabbing the header with grab_header() and after releasing with sysctl_head_finish(). This is needed if poll() is called in entries created by modules: currently only hostname and domainname support poll(), but this bug may be triggered when/if modules use it and if user called poll() in a file that doesn't support it. Dave Jones reported the following when using a syscall fuzzer while hibernating/resuming: RIP: 0010:[<ffffffff81233e3e>] [<ffffffff81233e3e>] proc_sys_poll+0x4e/0x90 RAX: 0000000000000145 RBX: ffff88020cab6940 RCX: 0000000000000000 RDX: ffffffff81233df0 RSI: 6b6b6b6b6b6b6b6b RDI: ffff88020cab6940 [ ... ] Code: 00 48 89 fb 48 89 f1 48 8b 40 30 4c 8b 60 e8 b8 45 01 00 00 49 83 7c 24 28 00 74 2e 49 8b 74 24 30 48 85 f6 74 24 48 85 c9 75 32 <8b> 16 b8 45 01 00 00 48 63 d2 49 39 d5 74 10 8b 06 48 98 48 89 If an entry goes away while we are polling() it, ctl_table may not exist anymore. Reported-by: Dave Jones <davej@xxxxxxxxxx> Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/proc_sysctl.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff -puN fs/proc/proc_sysctl.c~sysctl-protect-poll-in-entries-that-may-go-away fs/proc/proc_sysctl.c --- a/fs/proc/proc_sysctl.c~sysctl-protect-poll-in-entries-that-may-go-away +++ a/fs/proc/proc_sysctl.c @@ -527,20 +527,32 @@ static ssize_t proc_sys_write(struct fil static int proc_sys_open(struct inode *inode, struct file *filp) { + struct ctl_table_header *head = grab_header(inode); struct ctl_table *table = PROC_I(inode)->sysctl_entry; + /* sysctl was unregistered */ + if (IS_ERR(head)) + return PTR_ERR(head); + if (table->poll) filp->private_data = proc_sys_poll_event(table->poll); + sysctl_head_finish(head); + return 0; } static unsigned int proc_sys_poll(struct file *filp, poll_table *wait) { struct inode *inode = filp->f_path.dentry->d_inode; + struct ctl_table_header *head = grab_header(inode); struct ctl_table *table = PROC_I(inode)->sysctl_entry; - unsigned long event = (unsigned long)filp->private_data; unsigned int ret = DEFAULT_POLLMASK; + unsigned long event; + + /* sysctl was unregistered */ + if (IS_ERR(head)) + return POLLERR | POLLHUP; if (!table->proc_handler) goto out; @@ -548,6 +560,7 @@ static unsigned int proc_sys_poll(struct if (!table->poll) goto out; + event = (unsigned long)filp->private_data; poll_wait(filp, &table->poll->wait, wait); if (event != atomic_read(&table->poll->event)) { @@ -556,6 +569,8 @@ static unsigned int proc_sys_poll(struct } out: + sysctl_head_finish(head); + return ret; } _ Patches currently in -mm which might be from lucas.demarchi@xxxxxxxxxxxxxx are origin.patch linux-next.patch drivers-staging-telephony-ixjc-fix-warning-about-sequence-points.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html