The driver does not populate .reg_read callback for the non-active NVMem
because the file is supposed to be write-only. However, it turns out
NVMem subsystem does not yet support this and expects that the .reg_read
callback is provided. If user reads the binary attribute it triggers
NULL pointer dereference like this one:
BUG: kernel NULL pointer dereference, address: 0000000000000000
...
Call Trace:
bin_attr_nvmem_read+0x64/0x80
kernfs_fop_read+0xa7/0x180
vfs_read+0xbd/0x170
ksys_read+0x5a/0xd0
do_syscall_64+0x43/0x150
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fix this in the driver by providing .reg_read callback that always
returns an error.
Reported-by: Nicholas Johnson <nicholas.johnson-opensource@xxxxxxxxxxxxxx>
Fixes: e6b245ccd524 ("thunderbolt: Add support for host and device NVM firmware upgrade")
Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
Once NVMem subsystem starts supporting write-only NVMems we can drop this
one.
drivers/thunderbolt/switch.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index ad5479f21174..7d6ecc342508 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -348,6 +348,12 @@ static int tb_switch_nvm_read(void *priv, unsigned int offset, void *val,
return ret;
}
+static int tb_switch_nvm_no_read(void *priv, unsigned int offset, void *val,
+ size_t bytes)
+{
+ return -EPERM;
+}
+
static int tb_switch_nvm_write(void *priv, unsigned int offset, void *val,
size_t bytes)
{
@@ -393,6 +399,7 @@ static struct nvmem_device *register_nvmem(struct tb_switch *sw, int id,
config.read_only = true;
} else {
config.name = "nvm_non_active";
+ config.reg_read = tb_switch_nvm_no_read;
config.reg_write = tb_switch_nvm_write;
config.root_only = true;
}
--
2.25.0
