d4ad9a1cca
fgd->hash is saved and then freed, but is never reset to either ftrace_graph_hash nor ftrace_graph_notrace_hash. But if multiple writes are performed, then the freed hash could be accessed again. # cd /sys/kernel/debug/tracing # head -1000 available_filter_functions > /tmp/funcs # cat /tmp/funcs > set_graph_function Causes: general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC Modules linked in: [...] CPU: 2 PID: 1337 Comm: cat Not tainted 4.10.0-rc2-test-00010-g6b052e9 #32 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012 task: ffff880113a12200 task.stack: ffffc90001940000 RIP: 0010:free_ftrace_hash+0x7c/0x160 RSP: 0018:ffffc90001943db0 EFLAGS: 00010246 RAX: 6b6b6b6b6b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: 6b6b6b6b6b6b6b6b RDX: 0000000000000002 RSI: 0000000000000001 RDI: ffff8800ce1e1d40 RBP: ffff8800ce1e1d50 R08: 0000000000000000 R09: 0000000000006400 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8800ce1e1d40 R14: 0000000000004000 R15: 0000000000000001 FS: 00007f9408a07740(0000) GS:ffff88011e500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000aee1f0 CR3: 0000000116bb4000 CR4: 00000000001406e0 Call Trace: ? ftrace_graph_write+0x150/0x190 ? __vfs_write+0x1f6/0x210 ? __audit_syscall_entry+0x17f/0x200 ? rw_verify_area+0xdb/0x210 ? _cond_resched+0x2b/0x50 ? __sb_start_write+0xb4/0x130 ? vfs_write+0x1c8/0x330 ? SyS_write+0x62/0xf0 ? do_syscall_64+0xa3/0x1b0 ? entry_SYSCALL64_slow_path+0x25/0x25 Code: 01 48 85 db 0f 84 92 00 00 00 b8 01 00 00 00 d3 e0 85 c0 7e 3f 83 e8 01 48 8d 6f 10 45 31 e4 4c 8d 34 c5 08 00 00 00 49 8b 45 08 <4a> 8b 34 20 48 85 f6 74 13 48 8b 1e 48 89 ef e8 20 fa ff ff 48 RIP: free_ftrace_hash+0x7c/0x160 RSP: ffffc90001943db0 ---[ end trace 999b48216bf4b393 ]--- Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.