Messages in this thread | | | From | Nadav Amit <> | Subject | Re: [PATCH] modules: fix BUG when load module with rodata=n | Date | Tue, 18 Jun 2019 05:59:44 +0000 |
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> On Jun 16, 2019, at 11:59 PM, Yang Yingliang <yangyingliang@huawei.com> wrote: > > 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); > > @@ -2018,6 +2016,12 @@ void set_all_modules_text_ro(void) > static void module_enable_nx(const struct module *mod) { } > #endif > > +static void module_enable_x(const struct module *mod) > +{ > + frob_text(&mod->core_layout, set_memory_x); > + frob_text(&mod->init_layout, set_memory_x); > +} > + > #ifdef CONFIG_LIVEPATCH > /* > * Persist Elf information about a module. Copy the Elf header, > @@ -3616,6 +3620,7 @@ static int complete_formation(struct module *mod, struct load_info *info) > > module_enable_ro(mod, false); > module_enable_nx(mod); > + module_enable_x(mod); > > /* Mark state as coming so strong_try_module_get() ignores us, > * but kallsyms etc. can see us. */ > -- > 2.17.1
It does seem that I screwed up (thanks for fixing it!).
Makes me wonder why module_enable_ro() is needed to be called twice (excluding the write-protecting of the core_layout). I wonder since this patch would eliminate some calls to set_memory_x(), which indeed do not seem necessary.
Skimming 444d13ff10fb1 ("modules: add ro_after_init support”), I could not understand why.
Anyhow,
Reviewed-by: Nadav Amit <namit@vmware.com> | |