From 14843183ed0405a47a1e8762ce2b3ca2fac430fc Mon Sep 17 00:00:00 2001 From: Kenny Keslar Date: Fri, 12 Aug 2016 13:27:29 -0400 Subject: [PATCH] fs/proc/task_mmu.c: fix mm_access() mode parameter in pagemap_read() Orabug: 25308115 Backport of caaee6234d05a58c5b4d05e7bf766131b810a657 ("ptrace: use fsuid, fsgid, effective creds for fs access checks") to v4.1 failed to update the mode parameter in the mm_access() call in pagemap_read() to have one of the new PTRACE_MODE_*CREDS flags. Attempting to read any other process' pagemap results in a WARN() WARNING: CPU: 0 PID: 883 at kernel/ptrace.c:229 __ptrace_may_access+0x14a/0x160() denying ptrace access check without PTRACE_MODE_*CREDS Modules linked in: loop sg e1000 i2c_piix4 ppdev virtio_balloon virtio_pci parport_pc i2c_core virtio_ring ata_generic serio_raw pata_acpi virtio parport pcspkr floppy acpi_cpufreq ip_tables ext3 mbcache jbd sd_mod ata_piix crc32c_intel libata CPU: 0 PID: 883 Comm: cat Tainted: G W 4.1.12-51.el7uek.x86_64 #2 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 0000000000000286 00000000619f225a ffff88003b6fbc18 ffffffff81717021 ffff88003b6fbc70 ffffffff819be870 ffff88003b6fbc58 ffffffff8108477a 000000003b6fbc58 0000000000000001 ffff88003d287000 0000000000000001 Call Trace: [] dump_stack+0x63/0x81 [] warn_slowpath_common+0x8a/0xc0 [] warn_slowpath_fmt+0x55/0x70 [] __ptrace_may_access+0x14a/0x160 [] ptrace_may_access+0x32/0x50 [] mm_access+0x6d/0xb0 [] pagemap_read+0xe1/0x360 [] ? lru_cache_add_active_or_unevictable+0x2b/0xa0 [] __vfs_read+0x37/0x100 [] ? security_file_permission+0x84/0xa0 [] ? rw_verify_area+0x56/0xe0 [] vfs_read+0x86/0x140 [] SyS_read+0x55/0xd0 [] system_call_fastpath+0x12/0x71 Fixes: ab88ce5feca4 (ptrace: use fsuid, fsgid, effective creds for fs access checks) Signed-off-by: Kenny Keslar Cc: Roland McGrath Cc: Oleg Nesterov Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin (cherry picked from commit 5c576457aca8fc07bdb800a4589357801133f81b) Signed-off-by: Dhaval Giani --- fs/proc/task_mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 6dee68d013ff..32287fb146db 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1257,7 +1257,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, if (!pm.buffer) goto out_task; - mm = mm_access(task, PTRACE_MODE_READ); + mm = mm_access(task, PTRACE_MODE_READ_FSCREDS); ret = PTR_ERR(mm); if (!mm || IS_ERR(mm)) goto out_free; -- 2.50.1