On Tue, Nov 05, 2024 at 02:13:44PM +0300, Dmitry Antipov wrote: > Syzbot has reported the following BUG: > > kernel BUG at arch/x86/mm/physaddr.c:23! > Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI > CPU: 2 UID: 0 PID: 5869 Comm: repro Not tainted 6.12.0-rc5-next-20241101-syzkaller #0 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 > RIP: 0010:__phys_addr+0x16a/0x170 > Code: 40 a8 7a 8e 4c 89 f6 4c 89 fa e8 b1 4d aa 03 e9 45 ff ff ff e8 a7 1a 52 00 90 0f 0b e8 9f 1a 52 00 90 0f 0b e8 97 1a 52 00 90 <0f> 0b 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 > RSP: 0018:ffffc90002f7fda0 EFLAGS: 00010293 > RAX: ffffffff8143a369 RBX: 000000007ffffff2 RCX: ffff888106df5640 > RDX: 0000000000000000 RSI: 000000007ffffff2 RDI: 000000001fffffff > RBP: 1ffff11020df6d09 R08: ffffffff8143a305 R09: 1ffffffff203a1f6 > R10: dffffc0000000000 R11: fffffbfff203a1f7 R12: dffffc0000000000 > R13: fffffffffffffff2 R14: 000000007ffffff2 R15: ffff88802bc12d58 > FS: 00007f01bd1a7600(0000) GS:ffff888062900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: fffffffffffffff8 CR3: 0000000011f80000 CR4: 00000000000006f0 > Call Trace: > <TASK> > ? __die_body+0x5f/0xb0 > ? die+0x9e/0xc0 > ? do_trap+0x15a/0x3a0 > ? __phys_addr+0x16a/0x170 > ? do_error_trap+0x1dc/0x2c0 > ? __phys_addr+0x16a/0x170 > ? __pfx_do_error_trap+0x10/0x10 > ? handle_invalid_op+0x34/0x40 > ? __phys_addr+0x16a/0x170 > ? exc_invalid_op+0x38/0x50 > ? asm_exc_invalid_op+0x1a/0x20 > ? __phys_addr+0x105/0x170 > ? __phys_addr+0x169/0x170 > ? __phys_addr+0x16a/0x170 > ? free_bprm+0x2b5/0x300 > kfree+0x71/0x420 > ? free_bprm+0x295/0x300 > free_bprm+0x2b5/0x300 > do_execveat_common+0x3ae/0x750 > __x64_sys_execveat+0xc4/0xe0 > do_syscall_64+0xf3/0x230 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f01bd0c36a9 > Code: 5c c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 4f 37 0d 00 f7 d8 64 89 01 48 > RSP: 002b:00007fff034da398 EFLAGS: 00000246 ORIG_RAX: 0000000000000142 > RAX: ffffffffffffffda RBX: 0000000000403e00 RCX: 00007f01bd0c36a9 > RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000004 > RBP: 0000000000000001 R08: 0000000000001000 R09: 0000000000403e00 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff034da4b8 > R13: 00007fff034da4c8 R14: 0000000000401050 R15: 00007f01bd1dca80 > </TASK> > > Since 'bprm_add_fixup_comm()' may set 'bprm->argv0' to 'ERR_PTR()', > errno-lookalike invalid pointer should not be passed to 'kfree()'. > > Reported-by: syzbot+03e1af5c332f7e0eb84b@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?extid=03e1af5c332f7e0eb84b > Fixes: 7afad450c998 ("exec: fix up /proc/pid/comm in the execveat(AT_EMPTY_PATH) case") > Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx> > --- > fs/exec.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/exec.c b/fs/exec.c > index ef18eb0ea5b4..df70ed8e36fe 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1496,7 +1496,8 @@ static void free_bprm(struct linux_binprm *bprm) > if (bprm->interp != bprm->filename) > kfree(bprm->interp); > kfree(bprm->fdpath); > - kfree(bprm->argv0); > + if (!IS_ERR(bprm->argv0)) > + kfree(bprm->argv0); > kfree(bprm); > } It's better to avoid setting bprm->argv0 if strndup_user() fails. diff --git a/fs/exec.c b/fs/exec.c index ef18eb0ea5b4..9380e166eff5 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1504,6 +1504,7 @@ static int bprm_add_fixup_comm(struct linux_binprm *bprm, struct user_arg_ptr argv) { const char __user *p = get_user_arg_ptr(argv, 0); + char *argv0; /* * If p == NULL, let's just fall back to fdpath. @@ -1511,10 +1512,11 @@ static int bprm_add_fixup_comm(struct linux_binprm *bprm, if (!p) return 0; - bprm->argv0 = strndup_user(p, MAX_ARG_STRLEN); - if (IS_ERR(bprm->argv0)) - return PTR_ERR(bprm->argv0); + argv0 = strndup_user(p, MAX_ARG_STRLEN); + if (IS_ERR(argv0)) + return PTR_ERR(argv0); + bprm->argv0 = argv0; return 0; } -- Kiryl Shutsemau / Kirill A. Shutemov
