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[dfs][9pfs] fix unaligned access in P9_OF_OPS_GET/PUT #11876

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[dfs][9pfs] fix unaligned access in P9_OF_OPS_GET/PUT #11876

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58 changes: 38 additions & 20 deletions components/dfs/dfs_v1/filesystems/9pfs/dfs_9pfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,35 +39,48 @@ static rt_list_t _protocol_nodes = RT_LIST_OBJECT_INIT(_protocol_nodes);
static struct rt_spinlock _protocol_lock = { 0 };

#ifndef rt_le8_to_cpu
#define rt_le8_to_cpu
#define rt_le8_to_cpu(x) (x)
#endif
#ifndef rt_cpu_to_le8
#define rt_cpu_to_le8
#define rt_cpu_to_le8(x) (x)
#endif

#define P9_OF_OPS_GET(width, dir) \
rt_inline rt_uint##width##_t get_##dir##_##value##width##_of( \
struct p9_connection *conn, unsigned idx) \
{ \
rt_uint##width##_t *vp = (void *)&conn->dir##_buffer[idx]; \
return rt_le##width##_to_cpu(*vp); \
/*
* The 9P messages are not aligned inside `rx_buffer`/`tx_buffer`, a 64 bit
* field can start at any offset (e.g. the `length` field of an `Rstat` reply
* always starts at P9_MSG_STAT_LEN == 42). Dereferencing a casted pointer
* makes GCC emit `LDRD`/`STRD` on ARMv7-A, which faults on any address that
* is not 8 byte aligned, so always go through an aligned local variable.
*/
#define P9_OF_OPS_GET(width, dir) \
rt_inline rt_uint##width##_t get_##dir##_##value##width##_of( \
struct p9_connection *conn, unsigned idx) \
{ \
rt_uint##width##_t value; \
\
rt_memcpy(&value, &conn->dir##_buffer[idx], sizeof(value)); \
\
return rt_le##width##_to_cpu(value); \
}

#define P9_OF_OPS_PUT(width, dir) \
rt_inline void put_##dir##_##value##width##_of( \
struct p9_connection *conn, unsigned idx, \
rt_uint##width##_t value) \
{ \
rt_uint##width##_t *vp = (void *)&conn->dir##_buffer[idx]; \
*vp = rt_cpu_to_le##width(value); \
#define P9_OF_OPS_PUT(width, dir) \
rt_inline void put_##dir##_##value##width##_of( \
struct p9_connection *conn, unsigned idx, \
rt_uint##width##_t value) \
{ \
value = rt_cpu_to_le##width(value); \
\
rt_memcpy(&conn->dir##_buffer[idx], &value, sizeof(value)); \
}

#define P9_OPS_PUT(width) \
rt_inline rt_off_t put_value##width(struct p9_connection *conn, \
rt_off_t off, rt_uint##width##_t value) \
{ \
((rt_uint##width##_t *)(conn->tx_buffer + off))[0] = \
rt_cpu_to_le##width(value); \
value = rt_cpu_to_le##width(value); \
\
rt_memcpy(conn->tx_buffer + off, &value, sizeof(value)); \
\
return off + sizeof(value); \
}

Expand Down Expand Up @@ -367,7 +380,7 @@ rt_err_t dfs_9pfs_del_tag(struct p9_protocol *p9p)

static int p9_to_fs_err(int rc)
{
const int p9_err[] = {
const int p9_err[-P9_MSG_SIZE_TOO_BIG + 1] = {
[0] = RT_EOK,
[-P9_ERROR] = -EIO,
[-P9_UNKNOWN_VERSION] = -ENOSYS,
Expand All @@ -384,7 +397,12 @@ static int p9_to_fs_err(int rc)
[-P9_MSG_SIZE_TOO_BIG] = -ENOSPC,
};

return p9_err[-rc];
if (rc <= 0 && -rc < (int)(sizeof(p9_err) / sizeof(p9_err[0])))
{
return p9_err[-rc];
}

return -EIO;
}

static int p9_alloc_fid(struct p9_connection *conn)
Expand Down Expand Up @@ -547,7 +565,7 @@ rt_inline int p9_walk_subpath(struct p9_connection *conn, const char *path)

static int dfs_9pfs_open(struct dfs_file *fd)
{
int rc;
int rc = 0;
rt_uint32_t size;
rt_bool_t is_root;
struct p9_connection *conn;
Expand Down
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