From 7281491c594e7b8501eb5dfcf6cd3724f8a1b5b0 Mon Sep 17 00:00:00 2001 From: Jim Cromie Date: Mon, 19 Dec 2011 17:13:07 -0500 Subject: [PATCH] dynamic_debug: enlarge command/query write buffer Current query write buffer is 256 bytes, on stack. In comparison, the ddebug_query boot-arg is 1024. Allocate the buffer off heap, and enlarge it to 4096 bytes, big enough for ~100 queries (at 40 bytes each), and error out if not. This makes it play nicely with large query sets (to be added later). The buffer should be enough for most uses, and others should probably be split into subsets. [jbaron@redhat.com: changed USER_BUF_PAGE from 4095 -> 4096 ] Signed-off-by: Jim Cromie Signed-off-by: Jason Baron Signed-off-by: Greg Kroah-Hartman --- lib/dynamic_debug.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 86a9abb9a1ce..d8773dcd83c5 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -570,24 +570,32 @@ __setup("ddebug_query=", ddebug_setup_query); * File_ops->write method for /dynamic_debug/conrol. Gathers the * command text from userspace, parses and executes it. */ +#define USER_BUF_PAGE 4096 static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf, size_t len, loff_t *offp) { - char tmpbuf[256]; + char *tmpbuf; int ret; if (len == 0) return 0; - /* we don't check *offp -- multiple writes() are allowed */ - if (len > sizeof(tmpbuf)-1) + if (len > USER_BUF_PAGE - 1) { + pr_warn("expected <%d bytes into control\n", USER_BUF_PAGE); return -E2BIG; - if (copy_from_user(tmpbuf, ubuf, len)) + } + tmpbuf = kmalloc(len + 1, GFP_KERNEL); + if (!tmpbuf) + return -ENOMEM; + if (copy_from_user(tmpbuf, ubuf, len)) { + kfree(tmpbuf); return -EFAULT; + } tmpbuf[len] = '\0'; if (verbose) pr_info("read %d bytes from userspace\n", (int)len); ret = ddebug_exec_query(tmpbuf); + kfree(tmpbuf); if (ret) return ret; -- 2.39.5