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authorWilly Tarreau <w@1wt.eu>2018-05-11 08:11:44 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2018-05-17 09:27:47 -0700
commit7f7ccc2ccc2e70c6054685f5e3522efa81556830 (patch)
tree7309cb80e03910053c21d5b003ed1d6b2dcacc16 /include/linux/mm.h
parente6506eb241871d68647c53cb6d0a16299550ae97 (diff)
proc: do not access cmdline nor environ from file-backed areas
proc_pid_cmdline_read() and environ_read() directly access the target process' VM to retrieve the command line and environment. If this process remaps these areas onto a file via mmap(), the requesting process may experience various issues such as extra delays if the underlying device is slow to respond. Let's simply refuse to access file-backed areas in these functions. For this we add a new FOLL_ANON gup flag that is passed to all calls to access_remote_vm(). The code already takes care of such failures (including unmapped areas). Accesses via /proc/pid/mem were not changed though. This was assigned CVE-2018-1120. Note for stable backports: the patch may apply to kernels prior to 4.11 but silently miss one location; it must be checked that no call to access_remote_vm() keeps zero as the last argument. Reported-by: Qualys Security Advisory <qsa@qualys.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Oleg Nesterov <oleg@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/mm.h')
-rw-r--r--include/linux/mm.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1ac1f06a4be6..c080af584ddd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2493,6 +2493,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma,
#define FOLL_MLOCK 0x1000 /* lock present pages */
#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */
#define FOLL_COW 0x4000 /* internal GUP flag */
+#define FOLL_ANON 0x8000 /* don't do file mappings */
static inline int vm_fault_to_errno(int vm_fault, int foll_flags)
{