[PATCH v5 5.10/5.15] ata: libata-scsi: check cdb length for VARIABLE_LENGTH_CMD commands

[PATCH v5 5.10/5.15] ata: libata-scsi: check cdb length for VARIABLE_LENGTH_CMD commands

[Artem Sadovnikov]

No upstream commit exists for this commit.

Fuzzing of 5.10 stable branch reports a slab-out-of-bounds error in
ata_scsi_pass_thru.

The error is fixed in 5.18 by commit ce70fd9a551a ("scsi: core: Remove the
cmd field from struct scsi_request") upstream.
Backporting this commit would require significant changes to the code so
it is better to use a simple fix for that particular error.

The problem is that the length of the received SCSI command is not
validated if scsi_op == VARIABLE_LENGTH_CMD. It can lead to out-of-bounds
reading if the user sends a request with SCSI command of length less than
32.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Acked-by: Damien Le Moal <dlemoal@kernel.org>
Co-developed-by: Mikhail Ivanov <iwanov-23@bk.ru>
Signed-off-by: Mikhail Ivanov <iwanov-23@bk.ru>
Co-developed-by: Mikhail Ukhin <mish.uxin2012@yandex.ru>
Signed-off-by: Mikhail Ukhin <mish.uxin2012@yandex.ru>
Signed-off-by: Artem Sadovnikov <ancowi69@gmail.com>
---
Link: https://lore.kernel.org/lkml/20240711151546.341491-1-ancowi69@gmail.com/T/#u
unfortunately, stable@vger.kernel.org wasn't initially mentioned.
 drivers/ata/libata-scsi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 36f32fa052df..4397986db053 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3949,6 +3949,9 @@ static unsigned int ata_scsi_var_len_cdb_xlat(struct ata_queued_cmd *qc)
 	const u8 *cdb = scmd->cmnd;
 	const u16 sa = get_unaligned_be16(&cdb[8]);
 
+	if (scmd->cmd_len != 32)
+		return 1;
+
 	/*
 	 * if service action represents a ata pass-thru(32) command,
 	 * then pass it to ata_scsi_pass_thru handler.
-- 
2.34.1

[PATCH v5 5.10/5.15] ata: libata-scsi: check cdb length for VARIABLE_LENGTH_CMD commands

[Artem Sadovnikov]

Fuzzing of 5.10 stable branch reports a slab-out-of-bounds error in
ata_scsi_pass_thru.

The error is fixed in 5.18 by commit ce70fd9a551a ("scsi: core: Remove the
cmd field from struct scsi_request") upstream.

The problem is that the length of the received SCSI command is not
validated if scsi_op == VARIABLE_LENGTH_CMD. It can lead to out-of-bounds
reading if the user sends a request with SCSI command of length less than
32.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Signed-off-by: Artem Sadovnikov <ancowi69@gmail.com>
Signed-off-by: Mikhail Ivanov <iwanov-23@bk.ru>
Signed-off-by: Mikhail Ukhin <mish.uxin2012@yandex.ru>
---
 drivers/ata/libata-scsi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 36f32fa052df..4397986db053 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3949,6 +3949,9 @@ static unsigned int ata_scsi_var_len_cdb_xlat(struct ata_queued_cmd *qc)
 	const u8 *cdb = scmd->cmnd;
 	const u16 sa = get_unaligned_be16(&cdb[8]);
 
+	if (scmd->cmd_len != 32)
+		return 1;
+
 	/*
 	 * if service action represents a ata pass-thru(32) command,
 	 * then pass it to ata_scsi_pass_thru handler.
-- 
2.34.1

Re: [PATCH v5 5.10/5.15] ata: libata-scsi: check cdb length for VARIABLE_LENGTH_CMD commands

[Damien Le Moal]

On 7/12/24 00:15, Artem Sadovnikov wrote:
> Fuzzing of 5.10 stable branch reports a slab-out-of-bounds error in
> ata_scsi_pass_thru.
> 
> The error is fixed in 5.18 by commit ce70fd9a551a ("scsi: core: Remove the
> cmd field from struct scsi_request") upstream.
> 
> The problem is that the length of the received SCSI command is not
> validated if scsi_op == VARIABLE_LENGTH_CMD. It can lead to out-of-bounds
> reading if the user sends a request with SCSI command of length less than
> 32.
> 
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
> 
> Signed-off-by: Artem Sadovnikov <ancowi69@gmail.com>
> Signed-off-by: Mikhail Ivanov <iwanov-23@bk.ru>
> Signed-off-by: Mikhail Ukhin <mish.uxin2012@yandex.ru>

Looks good, so please feel free to add:

Acked-by: Damien Le Moal <dlemoal@kernel.org>

However, you did not address this patch to linux-stable and Greg, so it will go
nowhere as is since I cannot apply that to stable. So please check:

Documentation/process/stable-kernel-rules.rst

and see "option 2".

> ---
>  drivers/ata/libata-scsi.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 36f32fa052df..4397986db053 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3949,6 +3949,9 @@ static unsigned int ata_scsi_var_len_cdb_xlat(struct ata_queued_cmd *qc)
>  	const u8 *cdb = scmd->cmnd;
>  	const u16 sa = get_unaligned_be16(&cdb[8]);
>  
> +	if (scmd->cmd_len != 32)
> +		return 1;
> +
>  	/*
>  	 * if service action represents a ata pass-thru(32) command,
>  	 * then pass it to ata_scsi_pass_thru handler.

-- 
Damien Le Moal
Western Digital Research