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([129.170.197.108]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cb8d0ec694sm1251681485a.29.2026.02.25.03.52.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 03:52:21 -0800 (PST) From: pip-izony To: Greg Kroah-Hartman Cc: Seungjin Bae , Kyungtae Kim , Christophe JAILLET , Kees Cook , Yuping Luo , Felipe Balbi , Michal Nazarewicz , Alan Stern , Barry Song , linux-usb@vger.kernel.org Subject: [PATCH] usb: gadget: f_mass_storage: Fix potential integer overflow in check_command_size_in_blocks() Date: Wed, 25 Feb 2026 06:49:58 -0500 Message-ID: <20260225114957.1094146-2-eeodqql09@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Seungjin Bae The `check_command_size_in_blocks()` function calculates the data size in bytes by left shifting `common->data_size_from_cmnd` by the block size (`common->curlun->blkbits`). However, it does not validate whether this shift operation will cause an integer overflow. Initially, the block size is set up in `fsg_lun_open()` , and the `common->data_size_from_cmnd` is set up in `do_scsi_command()`. During initialization, there is no integer overflow check for the interaction between two variables. So if a malicious USB host sends a SCSI READ or WRITE command requesting a large amount of data (`common->data_size_from_cmnd`), the left shift operation can wrap around. This results in a truncated data size, which can bypass boundary checks and potentially lead to memory corruption or out-of-bounds accesses. Fix this by ensuring that `common->data_size_from_cmnd` is not greater than `(U32_MAX >> common->curlun->blkbits)` before performing the shift. Fixes: 144974e7f9e3 ("usb: gadget: mass_storage: support multi-luns with different logic block size") Signed-off-by: Seungjin Bae --- drivers/usb/gadget/function/f_mass_storage.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c index 6af96e2b44eb..12e7ef2e074e 100644 --- a/drivers/usb/gadget/function/f_mass_storage.c +++ b/drivers/usb/gadget/function/f_mass_storage.c @@ -1853,8 +1853,18 @@ static int check_command_size_in_blocks(struct fsg_common *common, int cmnd_size, enum data_direction data_dir, unsigned int mask, int needs_medium, const char *name) { - if (common->curlun) - common->data_size_from_cmnd <<= common->curlun->blkbits; + unsigned int blkbits; + + if (common->curlun) { + blkbits = common->curlun->blkbits; + if (cmnd_size > 10 && + common->data_size_from_cmnd > (U32_MAX >> blkbits)) { + common->phase_error = 1; + return -EINVAL; + } + common->data_size_from_cmnd <<= blkbits; + } + return check_command(common, cmnd_size, data_dir, mask, needs_medium, name); } -- 2.43.0