From: Chris Packham chris.packham@alliedtelesis.co.nz
commit 72a4a87da8f7bcf868b338615a814b6542f277f3 upstream.
When performing an I2C transfer where the last message was a write KASAN would complain:
BUG: KASAN: slab-out-of-bounds in mpc_i2c_do_action+0x154/0x630 Read of size 2 at addr c814e310 by task swapper/2/0
CPU: 2 PID: 0 Comm: swapper/2 Tainted: G B 5.16.0-rc8 #1 Call Trace: [e5ee9d50] [c08418e8] dump_stack_lvl+0x4c/0x6c (unreliable) [e5ee9d70] [c02f8a14] print_address_description.constprop.13+0x64/0x3b0 [e5ee9da0] [c02f9030] kasan_report+0x1f0/0x204 [e5ee9de0] [c0c76ee4] mpc_i2c_do_action+0x154/0x630 [e5ee9e30] [c0c782c4] mpc_i2c_isr+0x164/0x240 [e5ee9e60] [c00f3a04] __handle_irq_event_percpu+0xf4/0x3b0 [e5ee9ec0] [c00f3d40] handle_irq_event_percpu+0x80/0x110 [e5ee9f40] [c00f3e48] handle_irq_event+0x78/0xd0 [e5ee9f60] [c00fcfec] handle_fasteoi_irq+0x19c/0x370 [e5ee9fa0] [c00f1d84] generic_handle_irq+0x54/0x80 [e5ee9fc0] [c0006b54] __do_irq+0x64/0x200 [e5ee9ff0] [c0007958] __do_IRQ+0xe8/0x1c0 [c812dd50] [e3eaab20] 0xe3eaab20 [c812dd90] [c0007a4c] do_IRQ+0x1c/0x30 [c812dda0] [c0000c04] ExternalInput+0x144/0x160 --- interrupt: 500 at arch_cpu_idle+0x34/0x60 NIP: c000b684 LR: c000b684 CTR: c0019688 REGS: c812ddb0 TRAP: 0500 Tainted: G B (5.16.0-rc8) MSR: 00029002 <CE,EE,ME> CR: 22000488 XER: 20000000
GPR00: c10ef7fc c812de90 c80ff200 c2394718 00000001 00000001 c10e3f90 00000003 GPR08: 00000000 c0019688 c2394718 fc7d625b 22000484 00000000 21e17000 c208228c GPR16: e3e99284 00000000 ffffffff c2390000 c001bac0 c2082288 c812df60 c001ba60 GPR24: c23949c0 00000018 00080000 00000004 c80ff200 00000002 c2348ee4 c2394718 NIP [c000b684] arch_cpu_idle+0x34/0x60 LR [c000b684] arch_cpu_idle+0x34/0x60 --- interrupt: 500 [c812de90] [c10e3f90] rcu_eqs_enter.isra.60+0xc0/0x110 (unreliable) [c812deb0] [c10ef7fc] default_idle_call+0xbc/0x230 [c812dee0] [c00af0e8] do_idle+0x1c8/0x200 [c812df10] [c00af3c0] cpu_startup_entry+0x20/0x30 [c812df20] [c001e010] start_secondary+0x5d0/0xba0 [c812dff0] [c00028a0] __secondary_start+0x90/0xdc
This happened because we would overrun the i2c->msgs array on the final interrupt for the I2C STOP. This didn't happen if the last message was a read because there is no interrupt in that case. Ensure that we only access the current message if we are not processing a I2C STOP condition.
Fixes: 1538d82f4647 ("i2c: mpc: Interrupt driven transfer") Reported-by: Maxime Bizon mbizon@freebox.fr Signed-off-by: Chris Packham chris.packham@alliedtelesis.co.nz Signed-off-by: Wolfram Sang wsa@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/i2c/busses/i2c-mpc.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)
--- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -492,7 +492,7 @@ static void mpc_i2c_finish(struct mpc_i2
static void mpc_i2c_do_action(struct mpc_i2c *i2c) { - struct i2c_msg *msg = &i2c->msgs[i2c->curr_msg]; + struct i2c_msg *msg = NULL; int dir = 0; int recv_len = 0; u8 byte; @@ -501,10 +501,13 @@ static void mpc_i2c_do_action(struct mpc
i2c->cntl_bits &= ~(CCR_RSTA | CCR_MTX | CCR_TXAK);
- if (msg->flags & I2C_M_RD) - dir = 1; - if (msg->flags & I2C_M_RECV_LEN) - recv_len = 1; + if (i2c->action != MPC_I2C_ACTION_STOP) { + msg = &i2c->msgs[i2c->curr_msg]; + if (msg->flags & I2C_M_RD) + dir = 1; + if (msg->flags & I2C_M_RECV_LEN) + recv_len = 1; + }
switch (i2c->action) { case MPC_I2C_ACTION_RESTART: @@ -581,7 +584,7 @@ static void mpc_i2c_do_action(struct mpc break; }
- if (msg->len == i2c->byte_posn) { + if (msg && msg->len == i2c->byte_posn) { i2c->curr_msg++; i2c->byte_posn = 0;