Messages in this thread Patch in this message | | | Date | Wed, 19 Jun 2019 12:03:58 +0200 | From | Jessica Yu <> | Subject | Re: [PATCH] modules: fix BUG when load module with rodata=n |
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+++ Yang Yingliang [19/06/19 10:28 +0800]: > > >On 2019/6/18 21:48, Jessica Yu wrote: >>+++ Yang Yingliang [17/06/19 14:59 +0800]: >>>When loading a module with rodata=n, it causes an executing >>>NX-protected page BUG. >>> >>>[ 32.379191] kernel tried to execute NX-protected page - exploit >>>attempt? (uid: 0) >>>[ 32.382917] BUG: unable to handle page fault for address: >>>ffffffffc0005000 >>>[ 32.385947] #PF: supervisor instruction fetch in kernel mode >>>[ 32.387662] #PF: error_code(0x0011) - permissions violation >>>[ 32.389352] PGD 240c067 P4D 240c067 PUD 240e067 PMD 421a52067 >>>PTE 8000000421a53063 >>>[ 32.391396] Oops: 0011 [#1] SMP PTI >>>[ 32.392478] CPU: 7 PID: 2697 Comm: insmod Tainted: G >>>O 5.2.0-rc5+ #202 >>>[ 32.394588] Hardware name: QEMU Standard PC (i440FX + PIIX, >>>1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org >>>04/01/2014 >>>[ 32.398157] RIP: 0010:ko_test_init+0x0/0x1000 [ko_test] >>>[ 32.399662] Code: Bad RIP value. >>>[ 32.400621] RSP: 0018:ffffc900029f3ca8 EFLAGS: 00010246 >>>[ 32.402171] RAX: 0000000000000000 RBX: 0000000000000000 RCX: >>>0000000000000000 >>>[ 32.404332] RDX: 00000000000004c7 RSI: 0000000000000cc0 RDI: >>>ffffffffc0005000 >>>[ 32.406347] RBP: ffffffffc0005000 R08: ffff88842fbebc40 R09: >>>ffffffff810ede4a >>>[ 32.408392] R10: ffffea00108e3480 R11: 0000000000000000 R12: >>>ffff88842bee21a0 >>>[ 32.410472] R13: 0000000000000001 R14: 0000000000000001 R15: >>>ffffc900029f3e78 >>>[ 32.412609] FS: 00007fb4f0c0a700(0000) >>>GS:ffff88842fbc0000(0000) knlGS:0000000000000000 >>>[ 32.414722] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>[ 32.416290] CR2: ffffffffc0004fd6 CR3: 0000000421a90004 CR4: >>>0000000000020ee0 >>>[ 32.418471] Call Trace: >>>[ 32.419136] do_one_initcall+0x41/0x1df >>>[ 32.420199] ? _cond_resched+0x10/0x40 >>>[ 32.421433] ? kmem_cache_alloc_trace+0x36/0x160 >>>[ 32.422827] do_init_module+0x56/0x1f7 >>>[ 32.423946] load_module+0x1e67/0x2580 >>>[ 32.424947] ? __alloc_pages_nodemask+0x150/0x2c0 >>>[ 32.426413] ? map_vm_area+0x2d/0x40 >>>[ 32.427530] ? __vmalloc_node_range+0x1ef/0x260 >>>[ 32.428850] ? __do_sys_init_module+0x135/0x170 >>>[ 32.430060] ? _cond_resched+0x10/0x40 >>>[ 32.431249] __do_sys_init_module+0x135/0x170 >>>[ 32.432547] do_syscall_64+0x43/0x120 >>>[ 32.433853] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >>> >>>Because if rodata=n, set_memory_x() cann't be called, fix this by >>>calling set_memory_x in complete_formation(); >>> >>>Fixes: f2c65fb3221a ("x86/modules: Avoid breaking W^X while >>>loading modules") >>>Suggested-by: Jian Cheng <cj.chengjian@huawei.com> >>>Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> >>>--- >>>kernel/module.c | 9 +++++++-- >>>1 file changed, 7 insertions(+), 2 deletions(-) >>> >>>diff --git a/kernel/module.c b/kernel/module.c >>>index 80c7c09584cf..1a5d879573c3 100644 >>>--- a/kernel/module.c >>>+++ b/kernel/module.c >>>@@ -1949,12 +1949,10 @@ void module_enable_ro(const struct module >>>*mod, bool after_init) >>> set_vm_flush_reset_perms(mod->core_layout.base); >>> set_vm_flush_reset_perms(mod->init_layout.base); >>> frob_text(&mod->core_layout, set_memory_ro); >>>- frob_text(&mod->core_layout, set_memory_x); >>> >>> frob_rodata(&mod->core_layout, set_memory_ro); >>> >>> frob_text(&mod->init_layout, set_memory_ro); >>>- frob_text(&mod->init_layout, set_memory_x); >>> >>> frob_rodata(&mod->init_layout, set_memory_ro); >> >>Just a style-related nit: could you also please shrink down this chunk >>and remove the empty lines between the frob_* calls? >OK,I will do it in next version. > >> >>>@@ -2018,6 +2016,12 @@ void set_all_modules_text_ro(void) >>>static void module_enable_nx(const struct module *mod) { } >>>#endif >> >>And note that we will need a stub for module_enable_x() here as well. >module_enable_x() is outside of CONFIG_STRICT_MODULE_RWX.
Ah yeah you're right, my mistake. We need it outside of the CONFIG_STRICT_MODULE_RWX block anyway since module_alloc() on x86 allocates memory with PAGE_KERNEL now instead of PAGE_KERNEL_EXEC and we need to set text to executable regardless.
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