[v7,18/31] linux-user: Fix types in uaccess.c

Commit Message

Richard Henderson Feb. 12, 2021, 6:48 p.m. UTC

For copy_*_user, only 0 and -TARGET_EFAULT are returned; no need
to involve abi_long.  Use size_t for lengths.  Use bool for the
lock_user copy argument.  Use ssize_t for target_strlen, because
we can't overflow the host memory space.

Reviewed-by: Peter Maydell <[e-mail]>
Signed-off-by: Richard Henderson <[e-mail]>
---
 linux-user/qemu.h    | 14 ++++++--------
 linux-user/uaccess.c | 45 ++++++++++++++++++++++----------------------
 2 files changed, 29 insertions(+), 30 deletions(-)

Comments

Philippe Mathieu-Daudé Feb. 12, 2021, 8:34 p.m. UTC | #1

On 2/12/21 7:48 PM, Richard Henderson wrote:
> For copy_*_user, only 0 and -TARGET_EFAULT are returned; no need
> to involve abi_long.  Use size_t for lengths.  Use bool for the
> lock_user copy argument.  Use ssize_t for target_strlen, because
> we can't overflow the host memory space.
> 
> Reviewed-by: Peter Maydell <[e-mail]>
> Signed-off-by: Richard Henderson <[e-mail]>
> ---
>  linux-user/qemu.h    | 14 ++++++--------
>  linux-user/uaccess.c | 45 ++++++++++++++++++++++----------------------
>  2 files changed, 29 insertions(+), 30 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>

Patch

diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 36b58bd840..d25a5dafc0 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -7,8 +7,6 @@ 
 #include "exec/cpu_ldst.h"
 
 #undef DEBUG_REMAP
-#ifdef DEBUG_REMAP
-#endif /* DEBUG_REMAP */
 
 #include "exec/user/abitypes.h"
 
@@ -629,8 +627,8 @@  static inline bool access_ok(CPUState *cpu, int type,
  * buffers between the target and host.  These internally perform
  * locking/unlocking of the memory.
  */
-abi_long copy_from_user(void *hptr, abi_ulong gaddr, size_t len);
-abi_long copy_to_user(abi_ulong gaddr, void *hptr, size_t len);
+int copy_from_user(void *hptr, abi_ulong gaddr, size_t len);
+int copy_to_user(abi_ulong gaddr, void *hptr, size_t len);
 
 /* Functions for accessing guest memory.  The tget and tput functions
    read/write single values, byteswapping as necessary.  The lock_user function
@@ -640,13 +638,13 @@  abi_long copy_to_user(abi_ulong gaddr, void *hptr, size_t len);
 
 /* Lock an area of guest memory into the host.  If copy is true then the
    host area will have the same contents as the guest.  */
-void *lock_user(int type, abi_ulong guest_addr, long len, int copy);
+void *lock_user(int type, abi_ulong guest_addr, size_t len, bool copy);
 
 /* Unlock an area of guest memory.  The first LEN bytes must be
    flushed back to guest memory. host_ptr = NULL is explicitly
    allowed and does nothing. */
-#ifdef DEBUG_REMAP
-static inline void unlock_user(void *host_ptr, abi_ulong guest_addr, long len)
+#ifndef DEBUG_REMAP
+static inline void unlock_user(void *host_ptr, abi_ulong guest_addr, size_t len)
 { }
 #else
 void unlock_user(void *host_ptr, abi_ulong guest_addr, long len);
@@ -654,7 +652,7 @@  void unlock_user(void *host_ptr, abi_ulong guest_addr, long len);
 
 /* Return the length of a string in target memory or -TARGET_EFAULT if
    access error. */
-abi_long target_strlen(abi_ulong gaddr);
+ssize_t target_strlen(abi_ulong gaddr);
 
 /* Like lock_user but for null terminated strings.  */
 void *lock_user_string(abi_ulong guest_addr);
diff --git a/linux-user/uaccess.c b/linux-user/uaccess.c
index bba012ed15..76af6a92b1 100644
--- a/linux-user/uaccess.c
+++ b/linux-user/uaccess.c
@@ -4,7 +4,7 @@ 
 
 #include "qemu.h"
 
-void *lock_user(int type, abi_ulong guest_addr, long len, int copy)
+void *lock_user(int type, abi_ulong guest_addr, size_t len, bool copy)
 {
     if (!access_ok_untagged(type, guest_addr, len)) {
         return NULL;
@@ -26,7 +26,7 @@  void *lock_user(int type, abi_ulong guest_addr, long len, int copy)
 }
 
 #ifdef DEBUG_REMAP
-void unlock_user(void *host_ptr, abi_ulong guest_addr, long len);
+void unlock_user(void *host_ptr, abi_ulong guest_addr, size_t len);
 {
     if (!host_ptr) {
         return;
@@ -34,7 +34,7 @@  void unlock_user(void *host_ptr, abi_ulong guest_addr, long len);
     if (host_ptr == g2h_untagged(guest_addr)) {
         return;
     }
-    if (len > 0) {
+    if (len != 0) {
         memcpy(g2h_untagged(guest_addr), host_ptr, len);
     }
     g_free(host_ptr);
@@ -43,53 +43,53 @@  void unlock_user(void *host_ptr, abi_ulong guest_addr, long len);
 
 void *lock_user_string(abi_ulong guest_addr)
 {
-    abi_long len = target_strlen(guest_addr);
+    ssize_t len = target_strlen(guest_addr);
     if (len < 0) {
         return NULL;
     }
-    return lock_user(VERIFY_READ, guest_addr, (long)(len + 1), 1);
+    return lock_user(VERIFY_READ, guest_addr, (size_t)len + 1, 1);
 }
 
 /* copy_from_user() and copy_to_user() are usually used to copy data
  * buffers between the target and host.  These internally perform
  * locking/unlocking of the memory.
  */
-abi_long copy_from_user(void *hptr, abi_ulong gaddr, size_t len)
+int copy_from_user(void *hptr, abi_ulong gaddr, size_t len)
 {
-    abi_long ret = 0;
-    void *ghptr;
+    int ret = 0;
+    void *ghptr = lock_user(VERIFY_READ, gaddr, len, 1);
 
-    if ((ghptr = lock_user(VERIFY_READ, gaddr, len, 1))) {
+    if (ghptr) {
         memcpy(hptr, ghptr, len);
         unlock_user(ghptr, gaddr, 0);
-    } else
+    } else {
         ret = -TARGET_EFAULT;
-
+    }
     return ret;
 }
 
-
-abi_long copy_to_user(abi_ulong gaddr, void *hptr, size_t len)
+int copy_to_user(abi_ulong gaddr, void *hptr, size_t len)
 {
-    abi_long ret = 0;
-    void *ghptr;
+    int ret = 0;
+    void *ghptr = lock_user(VERIFY_WRITE, gaddr, len, 0);
 
-    if ((ghptr = lock_user(VERIFY_WRITE, gaddr, len, 0))) {
+    if (ghptr) {
         memcpy(ghptr, hptr, len);
         unlock_user(ghptr, gaddr, len);
-    } else
+    } else {
         ret = -TARGET_EFAULT;
+    }
 
     return ret;
 }
 
 /* Return the length of a string in target memory or -TARGET_EFAULT if
    access error  */
-abi_long target_strlen(abi_ulong guest_addr1)
+ssize_t target_strlen(abi_ulong guest_addr1)
 {
     uint8_t *ptr;
     abi_ulong guest_addr;
-    int max_len, len;
+    size_t max_len, len;
 
     guest_addr = guest_addr1;
     for(;;) {
@@ -101,11 +101,12 @@  abi_long target_strlen(abi_ulong guest_addr1)
         unlock_user(ptr, guest_addr, 0);
         guest_addr += len;
         /* we don't allow wrapping or integer overflow */
-        if (guest_addr == 0 || 
-            (guest_addr - guest_addr1) > 0x7fffffff)
+        if (guest_addr == 0 || (guest_addr - guest_addr1) > 0x7fffffff) {
             return -TARGET_EFAULT;
-        if (len != max_len)
+        }
+        if (len != max_len) {
             break;
+        }
     }
     return guest_addr - guest_addr1;
 }