Re: [PATCH] parisc: Increase the usage check of kmalloc allocated object a

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 9/14/22 08:43, Rolf Eike Beer wrote:
Am Mittwoch, 14. September 2022, 08:18:19 CEST schrieb Helge Deller:
On 9/14/22 08:04, Li zeming wrote:
In the case of memory allocation failure, no alignment operation is
required.

Signed-off-by: Li zeming <zeming@xxxxxxxxxxxx>
---

   drivers/parisc/iosapic.c | 4 +++-
   1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/parisc/iosapic.c b/drivers/parisc/iosapic.c
index 3a8c98615634..33de438916d3 100644
--- a/drivers/parisc/iosapic.c
+++ b/drivers/parisc/iosapic.c
@@ -229,7 +229,9 @@ static struct irt_entry *iosapic_alloc_irt(int
num_entries)>
   	 * 4-byte alignment on 32-bit kernels
   	 */

   	a = (unsigned long)kmalloc(sizeof(struct irt_entry) * num_entries
+ 8,
   	GFP_KERNEL);>
-	a = (a + 7UL) & ~7UL;
+	if (a)
+		a = (a + 7UL) & ~7UL;
+

As you said, the adjustment isn't required, but it's still ok.
So I think the additional "if" isn't necessary and so I'm not
applying your patch.

Anyway, thanks for your help to try to improve the code!

I was about to say the same, but from looking at the code I don't think what
is in there is correct either. The comment seems outdated, because
__assume_kmalloc_alignment, which is __alignof__(unsigned long long). This
code is untouched for the entire git history, so maybe we can just change the
whole thing to

   return kcalloc(num_entries, sizeof(struct irt_entry))

now?

Yes, your proposal is good.
Anyone want to send a patch (with a small comment that kcalloc() will return
at least the required 8-byte alignment)?

And these functions end up propagating an allocation error in this file and it
will never reach kernel/setup.c, which seems bad.

That part I don't understand.
The return value of iosapic_alloc_irt() is checked afterwards, but you probably
meant something else?

But I guess the only point where this really can go wrong if the PDC
returns an absurdly large number of entries.
Helge




[Index of Archives]     [Linux SoC]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux