From 01c9e2a9fc5ce7f0ce0e692aaf0c57fbaf224bfc Mon Sep 17 00:00:00 2001 From: Stephen Rothwell Date: Thu, 9 Jan 2020 18:39:12 +1100 Subject: [PATCH] tty: evh_bytechan: Fix out of bounds accesses MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 3670664b5da555a2a481449b3baafff113b0ac35 upstream. ev_byte_channel_send() assumes that its third argument is a 16 byte array. Some places where it is called it may not be (or we can't easily tell if it is). Newer compilers have started producing warnings about this, so make sure we actually pass a 16 byte array. There may be more elegant solutions to this, but the driver is quite old and hasn't been updated in many years. The warnings (from a powerpc allyesconfig build) are: In file included from include/linux/byteorder/big_endian.h:5, from arch/powerpc/include/uapi/asm/byteorder.h:14, from include/asm-generic/bitops/le.h:6, from arch/powerpc/include/asm/bitops.h:250, from include/linux/bitops.h:29, from include/linux/kernel.h:12, from include/asm-generic/bug.h:19, from arch/powerpc/include/asm/bug.h:109, from include/linux/bug.h:5, from include/linux/mmdebug.h:5, from include/linux/gfp.h:5, from include/linux/slab.h:15, from drivers/tty/ehv_bytechan.c:24: drivers/tty/ehv_bytechan.c: In function ‘ehv_bc_udbg_putc’: arch/powerpc/include/asm/epapr_hcalls.h:298:20: warning: array subscript 1 is outside array bounds of ‘const char[1]’ [-Warray-bounds] 298 | r6 = be32_to_cpu(p[1]); include/uapi/linux/byteorder/big_endian.h:40:51: note: in definition of macro ‘__be32_to_cpu’ 40 | #define __be32_to_cpu(x) ((__force __u32)(__be32)(x)) | ^ arch/powerpc/include/asm/epapr_hcalls.h:298:7: note: in expansion of macro ‘be32_to_cpu’ 298 | r6 = be32_to_cpu(p[1]); | ^~~~~~~~~~~ drivers/tty/ehv_bytechan.c:166:13: note: while referencing ‘data’ 166 | static void ehv_bc_udbg_putc(char c) | ^~~~~~~~~~~~~~~~ Fixes: dcd83aaff1c8 ("tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver") Signed-off-by: Stephen Rothwell Tested-by: Laurentiu Tudor [mpe: Trim warnings from change log] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200109183912.5fcb52aa@canb.auug.org.au Signed-off-by: Greg Kroah-Hartman --- drivers/tty/ehv_bytechan.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/tty/ehv_bytechan.c b/drivers/tty/ehv_bytechan.c index 769e0a5d1dfc..3c6dd06ec5fb 100644 --- a/drivers/tty/ehv_bytechan.c +++ b/drivers/tty/ehv_bytechan.c @@ -136,6 +136,21 @@ static int find_console_handle(void) return 1; } +static unsigned int local_ev_byte_channel_send(unsigned int handle, + unsigned int *count, + const char *p) +{ + char buffer[EV_BYTE_CHANNEL_MAX_BYTES]; + unsigned int c = *count; + + if (c < sizeof(buffer)) { + memcpy(buffer, p, c); + memset(&buffer[c], 0, sizeof(buffer) - c); + p = buffer; + } + return ev_byte_channel_send(handle, count, p); +} + /*************************** EARLY CONSOLE DRIVER ***************************/ #ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC @@ -154,7 +169,7 @@ static void byte_channel_spin_send(const char data) do { count = 1; - ret = ev_byte_channel_send(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE, + ret = local_ev_byte_channel_send(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE, &count, &data); } while (ret == EV_EAGAIN); } @@ -221,7 +236,7 @@ static int ehv_bc_console_byte_channel_send(unsigned int handle, const char *s, while (count) { len = min_t(unsigned int, count, EV_BYTE_CHANNEL_MAX_BYTES); do { - ret = ev_byte_channel_send(handle, &len, s); + ret = local_ev_byte_channel_send(handle, &len, s); } while (ret == EV_EAGAIN); count -= len; s += len; @@ -401,7 +416,7 @@ static void ehv_bc_tx_dequeue(struct ehv_bc_data *bc) CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE), EV_BYTE_CHANNEL_MAX_BYTES); - ret = ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail); + ret = local_ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail); /* 'len' is valid only if the return code is 0 or EV_EAGAIN */ if (!ret || (ret == EV_EAGAIN))