Re: [PATCH] ptrdiff_t is not uintptr_t, damnit

From: Anton Altaparmakov
Date: Sun Aug 19 2007 - 20:27:48 EST

On 19 Aug 2007, at 23:55, Al Viro wrote:
Use of ptrdiff_t in

- if (!access_ok(VERIFY_WRITE, u_tmp->rx_buf, u_tmp->len))
+ if (!access_ok(VERIFY_WRITE, (u8 __user *)
+ (ptrdiff_t) u_tmp- >rx_buf,
+ u_tmp->len))

is wrong; for one thing, it's a bad C (it's what uintptr_t is for; in general
we are not even promised that ptrdiff_t is large enough to hold a pointer,
just enough to hold a difference between two pointers within the same object).
For another, it confuses the fsck out of sparse.

Use unsigned long or uintptr_t instead. There are several places misusing
ptrdiff_t (one - in a very odd way; WTF did that cast to __user ptrdiff_t
in ntfs expect to happen, anyway?) Fixed...

My current NTFS code has this already fixed. I used unsigned long instead of uintptr_t though... Feel free to apply this though as I have no idea when I will have time/permission to push an update upstream...

And what the cast was doing I can't remember. I may well have just copied it from the VFS or I was perhaps trying to silence a warning and this happened to work... But yes I noticed that more recent versions of sparse complained about it and fixed it with an unsigned long cast.

Best regards,

Anton


Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
diff --git a/drivers/scsi/aacraid/commctrl.c b/drivers/scsi/aacraid/ commctrl.c
index 72b0393..1e6d7a9 100644
--- a/drivers/scsi/aacraid/commctrl.c
+++ b/drivers/scsi/aacraid/commctrl.c
@@ -391,7 +391,7 @@ static int close_getadapter_fib(struct aac_dev * dev, void __user *arg)
/*
* Extract the fibctx from the input parameters
*/
- if (fibctx->unique == (u32)(ptrdiff_t)arg) /* We found a winner */
+ if (fibctx->unique == (u32)(uintptr_t)arg) /* We found a winner */
break;
entry = entry->next;
fibctx = NULL;
@@ -590,7 +590,7 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
}
addr = (u64)upsg->sg[i].addr[0];
addr += ((u64)upsg->sg[i].addr[1]) << 32;
- sg_user[i] = (void __user *)(ptrdiff_t)addr;
+ sg_user[i] = (void __user *)(uintptr_t)addr;
sg_list[i] = p; // save so we can clean up later
sg_indx = i;

@@ -633,7 +633,7 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
rcode = -ENOMEM;
goto cleanup;
}
- sg_user[i] = (void __user *)(ptrdiff_t)usg->sg[i].addr;
+ sg_user[i] = (void __user *)(uintptr_t)usg->sg[i].addr;
sg_list[i] = p; // save so we can clean up later
sg_indx = i;

@@ -664,7 +664,7 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
if (actual_fibsize64 == fibsize) {
struct user_sgmap64* usg = (struct user_sgmap64 *)upsg;
for (i = 0; i < upsg->count; i++) {
- u64 addr;
+ uintptr_t addr;
void* p;
/* Does this really need to be GFP_DMA? */
p = kmalloc(usg->sg[i].count,GFP_KERNEL|__GFP_DMA);
@@ -676,7 +676,7 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
}
addr = (u64)usg->sg[i].addr[0];
addr += ((u64)usg->sg[i].addr[1]) << 32;
- sg_user[i] = (void __user *)(ptrdiff_t)addr;
+ sg_user[i] = (void __user *)addr;
sg_list[i] = p; // save so we can clean up later
sg_indx = i;

@@ -704,7 +704,7 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
rcode = -ENOMEM;
goto cleanup;
}
- sg_user[i] = (void __user *)(ptrdiff_t)upsg->sg[i].addr;
+ sg_user[i] = (void __user *)(uintptr_t)upsg->sg[i].addr;
sg_list[i] = p; // save so we can clean up later
sg_indx = i;

diff --git a/drivers/scsi/aacraid/comminit.c b/drivers/scsi/aacraid/ comminit.c
index 3009ad8..8736813 100644
--- a/drivers/scsi/aacraid/comminit.c
+++ b/drivers/scsi/aacraid/comminit.c
@@ -110,7 +110,7 @@ static int aac_alloc_comm(struct aac_dev *dev, void **commaddr, unsigned long co
/*
* Align the beginning of Headers to commalign
*/
- align = (commalign - ((ptrdiff_t)(base) & (commalign - 1)));
+ align = (commalign - ((uintptr_t)(base) & (commalign - 1)));
base = base + align;
phys = phys + align;
/*
diff --git a/drivers/scsi/aacraid/dpcsup.c b/drivers/scsi/aacraid/ dpcsup.c
index fcd25f7..e6032ff 100644
--- a/drivers/scsi/aacraid/dpcsup.c
+++ b/drivers/scsi/aacraid/dpcsup.c
@@ -254,7 +254,7 @@ unsigned int aac_intr_normal(struct aac_dev * dev, u32 Index)
kfree (fib);
return 1;
}
- memcpy(hw_fib, (struct hw_fib *)(((ptrdiff_t)(dev->regs.sa)) +
+ memcpy(hw_fib, (struct hw_fib *)(((uintptr_t)(dev->regs.sa)) +
(index & ~0x00000002L)), sizeof(struct hw_fib));
INIT_LIST_HEAD(&fib->fiblink);
fib->type = FSAFS_NTC_FIB_CONTEXT;
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index c55459c..b3518ca 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -184,14 +184,14 @@ static int spidev_message(struct spidev_data *spidev,
if (u_tmp->rx_buf) {
k_tmp->rx_buf = buf;
if (!access_ok(VERIFY_WRITE, (u8 __user *)
- (ptrdiff_t) u_tmp->rx_buf,
+ (uintptr_t) u_tmp->rx_buf,
u_tmp->len))
goto done;
}
if (u_tmp->tx_buf) {
k_tmp->tx_buf = buf;
if (copy_from_user(buf, (const u8 __user *)
- (ptrdiff_t) u_tmp->tx_buf,
+ (uintptr_t) u_tmp->tx_buf,
u_tmp->len))
goto done;
}
@@ -224,7 +224,7 @@ static int spidev_message(struct spidev_data *spidev,
for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
if (u_tmp->rx_buf) {
if (__copy_to_user((u8 __user *)
- (ptrdiff_t) u_tmp->rx_buf, buf,
+ (uintptr_t) u_tmp->rx_buf, buf,
u_tmp->len)) {
status = -EFAULT;
goto done;
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index ffcc504..a9103ce 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -362,7 +362,7 @@ static inline void ntfs_fault_in_pages_readable (const char __user *uaddr,
volatile char c;

/* Set @end to the first byte outside the last page we care about. */
- end = (const char __user*)PAGE_ALIGN((ptrdiff_t __user)uaddr + bytes);
+ end = (const char __user*)PAGE_ALIGN((uintptr_t)uaddr + bytes);

while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
;
diff --git a/include/linux/types.h b/include/linux/types.h
index 0351bf2..efdec19 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -40,6 +40,8 @@ typedef __kernel_gid32_t gid_t;
typedef __kernel_uid16_t uid16_t;
typedef __kernel_gid16_t gid16_t;

+typedef unsigned long uintptr_t;
+
#ifdef CONFIG_UID16
/* This is defined by include/asm-{arch}/posix_types.h */
typedef __kernel_old_uid_t old_uid_t;
-
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Best regards,

Anton
--
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer, http://www.linux-ntfs.org/


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