2021-11-17 22:05:30

by Christophe JAILLET

Subject: [PATCH] i3c/master: Fix a potentially infinite loop in 'hci_dat_v1_get_index()'

The code in 'hci_dat_v1_get_index()' really looks like a hand coded version
of 'for_each_set_bit()', except that a +1 is missing when searching for the
next set bit.

This really looks odd and it seems that it will loop until 'dat_w0_read()'
returns the expected result.

So use 'for_each_set_bit()' instead. It is less verbose and should be more
correct.

Fixes: 9ad9a52cce28 ("i3c/master: introduce the mipi-i3c-hci driver")
Signed-off-by: Christophe JAILLET <[email protected]>
---
Speculative fix. Untested.
---
drivers/i3c/master/mipi-i3c-hci/dat_v1.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/dat_v1.c b/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
index 783e551a2c85..97bb49ff5b53 100644
--- a/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
@@ -160,9 +160,7 @@ static int hci_dat_v1_get_index(struct i3c_hci *hci, u8 dev_addr)
unsigned int dat_idx;
u32 dat_w0;

- for (dat_idx = find_first_bit(hci->DAT_data, hci->DAT_entries);
- dat_idx < hci->DAT_entries;
- dat_idx = find_next_bit(hci->DAT_data, hci->DAT_entries, dat_idx)) {
+ for_each_set_bit(dat_idx, hci->DAT_data, hci->DAT_entries) {
dat_w0 = dat_w0_read(dat_idx);
if (FIELD_GET(DAT_0_DYNAMIC_ADDRESS, dat_w0) == dev_addr)
return dat_idx;
--
2.30.2

2021-11-19 23:16:23

by Nicolas Pitre

Subject: Re: [PATCH] i3c/master: Fix a potentially infinite loop in 'hci_dat_v1_get_index()'

On Wed, 17 Nov 2021, Christophe JAILLET wrote:

> The code in 'hci_dat_v1_get_index()' really looks like a hand coded version
> of 'for_each_set_bit()', except that a +1 is missing when searching for the
> next set bit.
>
> This really looks odd and it seems that it will loop until 'dat_w0_read()'
> returns the expected result.
>
> So use 'for_each_set_bit()' instead. It is less verbose and should be more
> correct.
>
> Fixes: 9ad9a52cce28 ("i3c/master: introduce the mipi-i3c-hci driver")
> Signed-off-by: Christophe JAILLET <[email protected]>

Acked-by: Nicolas Pitre <[email protected]>

> ---
> Speculative fix. Untested.
> ---
> drivers/i3c/master/mipi-i3c-hci/dat_v1.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/i3c/master/mipi-i3c-hci/dat_v1.c b/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
> index 783e551a2c85..97bb49ff5b53 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
> +++ b/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
> @@ -160,9 +160,7 @@ static int hci_dat_v1_get_index(struct i3c_hci *hci, u8 dev_addr)
> unsigned int dat_idx;
> u32 dat_w0;
>
> - for (dat_idx = find_first_bit(hci->DAT_data, hci->DAT_entries);
> - dat_idx < hci->DAT_entries;
> - dat_idx = find_next_bit(hci->DAT_data, hci->DAT_entries, dat_idx)) {
> + for_each_set_bit(dat_idx, hci->DAT_data, hci->DAT_entries) {
> dat_w0 = dat_w0_read(dat_idx);
> if (FIELD_GET(DAT_0_DYNAMIC_ADDRESS, dat_w0) == dev_addr)
> return dat_idx;
> --
> 2.30.2
>
>
> --
> linux-i3c mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-i3c
>

2021-12-10 15:39:27

by Alexandre Belloni

Subject: Re: [PATCH] i3c/master: Fix a potentially infinite loop in 'hci_dat_v1_get_index()'

On Wed, 17 Nov 2021 23:05:23 +0100, Christophe JAILLET wrote:
> The code in 'hci_dat_v1_get_index()' really looks like a hand coded version
> of 'for_each_set_bit()', except that a +1 is missing when searching for the
> next set bit.
>
> This really looks odd and it seems that it will loop until 'dat_w0_read()'
> returns the expected result.
>
> [...]

Applied, thanks!

[1/1] i3c/master: Fix a potentially infinite loop in 'hci_dat_v1_get_index()'
commit: 3f43926f271287fb1744c9ac9ae1122497f2b0c2

Best regards,
--
Alexandre Belloni <[email protected]>