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| author | Al Viro <viro@ftp.linux.org.uk> | 2010-09-20 15:13:09 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-09-20 10:44:37 -0700 |
| commit | 5f4ad04a1e805d14de080ff9d5384b4d20518a9a (patch) | |
| tree | 63252b79b48b7dfd29d9a8081a34c858dab1de74 /arch/frv | |
| parent | 20cd514d0f3d288d968217028ca67b70e707d896 (diff) | |
| download | lwn-5f4ad04a1e805d14de080ff9d5384b4d20518a9a.tar.gz lwn-5f4ad04a1e805d14de080ff9d5384b4d20518a9a.zip | |
frv: fix address verification holes in setup_frame/setup_rt_frame
a) sa_handler might be maliciously set to point to kernel memory;
blindly dereferencing it in FDPIC case is a Bad Idea(tm).
b) I'm not sure you need that set_fs(USER_DS) there at all, but if you
do, you'd better do it *before* checking the frame you've decided to
use with access_ok(), lest sigaltstack() becomes a convenient
roothole.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/frv')
| -rw-r--r-- | arch/frv/kernel/signal.c | 38 |
1 files changed, 22 insertions, 16 deletions
diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c index 7fc29615ef01..5fb2d0661c78 100644 --- a/arch/frv/kernel/signal.c +++ b/arch/frv/kernel/signal.c @@ -253,6 +253,8 @@ static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set) struct sigframe __user *frame; int rsig; + set_fs(USER_DS); + frame = get_sigframe(ka, sizeof(*frame)); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) @@ -296,22 +298,23 @@ static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set) (unsigned long) (frame->retcode + 2)); } - /* set up registers for signal handler */ - __frame->sp = (unsigned long) frame; - __frame->lr = (unsigned long) &frame->retcode; - __frame->gr8 = sig; - + /* Set up registers for the signal handler */ if (current->personality & FDPIC_FUNCPTRS) { struct fdpic_func_descriptor __user *funcptr = (struct fdpic_func_descriptor __user *) ka->sa.sa_handler; - __get_user(__frame->pc, &funcptr->text); - __get_user(__frame->gr15, &funcptr->GOT); + struct fdpic_func_descriptor desc; + if (copy_from_user(&desc, funcptr, sizeof(desc))) + goto give_sigsegv; + __frame->pc = desc.text; + __frame->gr15 = desc.GOT; } else { __frame->pc = (unsigned long) ka->sa.sa_handler; __frame->gr15 = 0; } - set_fs(USER_DS); + __frame->sp = (unsigned long) frame; + __frame->lr = (unsigned long) &frame->retcode; + __frame->gr8 = sig; /* the tracer may want to single-step inside the handler */ if (test_thread_flag(TIF_SINGLESTEP)) @@ -341,6 +344,8 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, struct rt_sigframe __user *frame; int rsig; + set_fs(USER_DS); + frame = get_sigframe(ka, sizeof(*frame)); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) @@ -395,22 +400,23 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, } /* Set up registers for signal handler */ - __frame->sp = (unsigned long) frame; - __frame->lr = (unsigned long) &frame->retcode; - __frame->gr8 = sig; - __frame->gr9 = (unsigned long) &frame->info; - if (current->personality & FDPIC_FUNCPTRS) { struct fdpic_func_descriptor __user *funcptr = (struct fdpic_func_descriptor __user *) ka->sa.sa_handler; - __get_user(__frame->pc, &funcptr->text); - __get_user(__frame->gr15, &funcptr->GOT); + struct fdpic_func_descriptor desc; + if (copy_from_user(&desc, funcptr, sizeof(desc))) + goto give_sigsegv; + __frame->pc = desc.text; + __frame->gr15 = desc.GOT; } else { __frame->pc = (unsigned long) ka->sa.sa_handler; __frame->gr15 = 0; } - set_fs(USER_DS); + __frame->sp = (unsigned long) frame; + __frame->lr = (unsigned long) &frame->retcode; + __frame->gr8 = sig; + __frame->gr9 = (unsigned long) &frame->info; /* the tracer may want to single-step inside the handler */ if (test_thread_flag(TIF_SINGLESTEP)) |