[19/67] oprofile: Fix uninitialized memory access when writing to writing to oprofilefs
From: Greg KH <gregkh@suse.de>
Date: 2012-01-03 23:08:09
Also in:
lkml
3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Robert Richter <redacted> commit 913050b91eb94f194392dd797b1ff3779f606ac0 upstream. If oprofilefs_ulong_from_user() is called with count equals zero, *val remains unchanged. Depending on the implementation it might be uninitialized. Change oprofilefs_ulong_from_user()'s interface to return count on success. Thus, we are able to return early if count equals zero which avoids using *val uninitialized. Fixing all users of oprofilefs_ulong_ from_user(). This follows write syscall implementation when count is zero: "If count is zero ... [and if] no errors are detected, 0 will be returned without causing any other effect." (man 2 write) Reported-By: Mike Waychison <redacted> Signed-off-by: Robert Richter <redacted> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: oprofile-list <redacted> Link: http://lkml.kernel.org/r/20111219153830.GH16765@erda.amd.com Signed-off-by: Ingo Molnar <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- arch/s390/oprofile/init.c | 2 +- drivers/oprofile/oprofile_files.c | 7 ++++--- drivers/oprofile/oprofilefs.c | 11 +++++++++-- 3 files changed, 14 insertions(+), 6 deletions(-)
--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c@@ -90,7 +90,7 @@ static ssize_t hwsampler_write(struct fi return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; if (oprofile_started) --- a/drivers/oprofile/oprofile_files.c +++ b/drivers/oprofile/oprofile_files.c
@@ -45,7 +45,7 @@ static ssize_t timeout_write(struct file return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; retval = oprofile_set_timeout(val);
@@ -84,7 +84,7 @@ static ssize_t depth_write(struct file * return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; retval = oprofile_set_ulong(&oprofile_backtrace_depth, val);
@@ -141,9 +141,10 @@ static ssize_t enable_write(struct file return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; + retval = 0; if (val) retval = oprofile_start(); else --- a/drivers/oprofile/oprofilefs.c +++ b/drivers/oprofile/oprofilefs.c
@@ -60,6 +60,13 @@ ssize_t oprofilefs_ulong_to_user(unsigne } +/* + * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains + * unchanged and might be uninitialized. This follows write syscall + * implementation when count is zero: "If count is zero ... [and if] + * no errors are detected, 0 will be returned without causing any + * other effect." (man 2 write) + */ int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count) { char tmpbuf[TMPBUFSIZE];
@@ -79,7 +86,7 @@ int oprofilefs_ulong_from_user(unsigned spin_lock_irqsave(&oprofilefs_lock, flags); *val = simple_strtoul(tmpbuf, NULL, 0); spin_unlock_irqrestore(&oprofilefs_lock, flags); - return 0; + return count; }
@@ -99,7 +106,7 @@ static ssize_t ulong_write_file(struct f return -EINVAL; retval = oprofilefs_ulong_from_user(&value, buf, count); - if (retval) + if (retval <= 0) return retval; retval = oprofile_set_ulong(file->private_data, value);