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generic: 6.6: fix and simplify blkdevparts= cmdline parsing
Import pending patch to fix the cmdline parsing of the "blkdevparts=" parameter which has been broken somewhen between Linux 6.1 and Linux 6.6. Signed-off-by: Daniel Golle <daniel@makrotopia.org>
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Daniel Golle
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a5a941a997
commit
fb2475e6bd
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From patchwork Sun Apr 21 07:39:52 2024
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Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 7bit
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X-Patchwork-Submitter: INAGAKI Hiroshi <musashino.open@gmail.com>
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X-Patchwork-Id: 13637306
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From: INAGAKI Hiroshi <musashino.open@gmail.com>
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To: axboe@kernel.dk
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Cc: yang.yang29@zte.com,
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justinstitt@google.com,
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xu.panda@zte.com.cn,
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linux-block@vger.kernel.org,
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linux-kernel@vger.kernel.org,
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INAGAKI Hiroshi <musashino.open@gmail.com>,
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Naohiro Aota <naota@elisp.net>
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Subject: [PATCH] block: fix and simplify blkdevparts= cmdline parsing
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Date: Sun, 21 Apr 2024 16:39:52 +0900
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Message-ID: <20240421074005.565-1-musashino.open@gmail.com>
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Fix the cmdline parsing of the "blkdevparts=" parameter using strsep(),
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which makes the code simpler.
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Before commit 146afeb235cc ("block: use strscpy() to instead of
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strncpy()"), we used a strncpy() to copy a block device name and partition
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names. The commit simply replaced a strncpy() and NULL termination with
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a strscpy(). It did not update calculations of length passed to strscpy().
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While the length passed to strncpy() is just a length of valid characters
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without NULL termination ('\0'), strscpy() takes it as a length of the
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destination buffer, including a NULL termination.
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Since the source buffer is not necessarily NULL terminated, the current
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code copies "length - 1" characters and puts a NULL character in the
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destination buffer. It replaces the last character with NULL and breaks
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the parsing.
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As an example, that buffer will be passed to parse_parts() and breaks
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parsing sub-partitions due to the missing ')' at the end, like the
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following.
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example (Check Point V-80 & OpenWrt):
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- Linux Kernel 6.6
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[ 0.000000] Kernel command line: console=ttyS0,115200 earlycon=uart8250,mmio32,0xf0512000 crashkernel=30M mvpp2x.queue_mode=1 blkdevparts=mmcblk1:48M@10M(kernel-1),1M(dtb-1),720M(rootfs-1),48M(kernel-2),1M(dtb-2),720M(rootfs-2),300M(default_sw),650M(logs),1M(preset_cfg),1M(adsl),-(storage) maxcpus=4
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...
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[ 0.884016] mmc1: new HS200 MMC card at address 0001
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[ 0.889951] mmcblk1: mmc1:0001 004GA0 3.69 GiB
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[ 0.895043] cmdline partition format is invalid.
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[ 0.895704] mmcblk1: p1
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[ 0.903447] mmcblk1boot0: mmc1:0001 004GA0 2.00 MiB
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[ 0.908667] mmcblk1boot1: mmc1:0001 004GA0 2.00 MiB
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[ 0.913765] mmcblk1rpmb: mmc1:0001 004GA0 512 KiB, chardev (248:0)
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1. "48M@10M(kernel-1),..." is passed to strscpy() with length=17
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from parse_parts()
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2. strscpy() returns -E2BIG and the destination buffer has
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"48M@10M(kernel-1\0"
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3. "48M@10M(kernel-1\0" is passed to parse_subpart()
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4. parse_subpart() fails to find ')' when parsing a partition name,
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and returns error
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- Linux Kernel 6.1
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[ 0.000000] Kernel command line: console=ttyS0,115200 earlycon=uart8250,mmio32,0xf0512000 crashkernel=30M mvpp2x.queue_mode=1 blkdevparts=mmcblk1:48M@10M(kernel-1),1M(dtb-1),720M(rootfs-1),48M(kernel-2),1M(dtb-2),720M(rootfs-2),300M(default_sw),650M(logs),1M(preset_cfg),1M(adsl),-(storage) maxcpus=4
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...
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[ 0.953142] mmc1: new HS200 MMC card at address 0001
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[ 0.959114] mmcblk1: mmc1:0001 004GA0 3.69 GiB
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[ 0.964259] mmcblk1: p1(kernel-1) p2(dtb-1) p3(rootfs-1) p4(kernel-2) p5(dtb-2) 6(rootfs-2) p7(default_sw) p8(logs) p9(preset_cfg) p10(adsl) p11(storage)
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[ 0.979174] mmcblk1boot0: mmc1:0001 004GA0 2.00 MiB
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[ 0.984674] mmcblk1boot1: mmc1:0001 004GA0 2.00 MiB
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[ 0.989926] mmcblk1rpmb: mmc1:0001 004GA0 512 KiB, chardev (248:0
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By the way, strscpy() takes a length of destination buffer and it is
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often confusing when copying characters with a specified length. Using
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strsep() helps to separate the string by the specified character. Then,
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we can use strscpy() naturally with the size of the destination buffer.
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Separating the string on the fly is also useful to omit the redundant
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string copy, reducing memory usage and improve the code readability.
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Fixes: 146afeb235cc ("block: use strscpy() to instead of strncpy()")
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Suggested-by: Naohiro Aota <naota@elisp.net>
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Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>
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Reviewed-by: Daniel Golle <daniel@makrotopia.org>
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---
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block/partitions/cmdline.c | 49 ++++++++++----------------------------
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1 file changed, 12 insertions(+), 37 deletions(-)
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--- a/block/partitions/cmdline.c
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+++ b/block/partitions/cmdline.c
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@@ -70,8 +70,8 @@ static int parse_subpart(struct cmdline_
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}
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if (*partdef == '(') {
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- int length;
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- char *next = strchr(++partdef, ')');
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+ partdef++;
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+ char *next = strsep(&partdef, ")");
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if (!next) {
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pr_warn("cmdline partition format is invalid.");
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@@ -79,11 +79,7 @@ static int parse_subpart(struct cmdline_
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goto fail;
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}
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- length = min_t(int, next - partdef,
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- sizeof(new_subpart->name) - 1);
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- strscpy(new_subpart->name, partdef, length);
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-
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- partdef = ++next;
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+ strscpy(new_subpart->name, next, sizeof(new_subpart->name));
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} else
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new_subpart->name[0] = '\0';
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@@ -117,14 +113,12 @@ static void free_subpart(struct cmdline_
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}
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}
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-static int parse_parts(struct cmdline_parts **parts, const char *bdevdef)
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+static int parse_parts(struct cmdline_parts **parts, char *bdevdef)
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{
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int ret = -EINVAL;
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char *next;
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- int length;
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struct cmdline_subpart **next_subpart;
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struct cmdline_parts *newparts;
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- char buf[BDEVNAME_SIZE + 32 + 4];
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*parts = NULL;
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@@ -132,28 +126,19 @@ static int parse_parts(struct cmdline_pa
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if (!newparts)
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return -ENOMEM;
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- next = strchr(bdevdef, ':');
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+ next = strsep(&bdevdef, ":");
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if (!next) {
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pr_warn("cmdline partition has no block device.");
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goto fail;
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}
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- length = min_t(int, next - bdevdef, sizeof(newparts->name) - 1);
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- strscpy(newparts->name, bdevdef, length);
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+ strscpy(newparts->name, next, sizeof(newparts->name));
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newparts->nr_subparts = 0;
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next_subpart = &newparts->subpart;
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- while (next && *(++next)) {
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- bdevdef = next;
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- next = strchr(bdevdef, ',');
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-
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- length = (!next) ? (sizeof(buf) - 1) :
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- min_t(int, next - bdevdef, sizeof(buf) - 1);
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-
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- strscpy(buf, bdevdef, length);
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-
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- ret = parse_subpart(next_subpart, buf);
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+ while ((next = strsep(&bdevdef, ","))) {
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+ ret = parse_subpart(next_subpart, next);
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if (ret)
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goto fail;
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@@ -199,24 +184,17 @@ static int cmdline_parts_parse(struct cm
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*parts = NULL;
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- next = pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
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+ pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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next_parts = parts;
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- while (next && *pbuf) {
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- next = strchr(pbuf, ';');
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- if (next)
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- *next = '\0';
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-
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- ret = parse_parts(next_parts, pbuf);
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+ while ((next = strsep(&pbuf, ";"))) {
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+ ret = parse_parts(next_parts, next);
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if (ret)
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goto fail;
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- if (next)
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- pbuf = ++next;
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-
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next_parts = &(*next_parts)->next_parts;
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}
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@@ -250,7 +228,6 @@ static struct cmdline_parts *bdev_parts;
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static int add_part(int slot, struct cmdline_subpart *subpart,
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struct parsed_partitions *state)
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{
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- int label_min;
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struct partition_meta_info *info;
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char tmp[sizeof(info->volname) + 4];
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@@ -262,9 +239,7 @@ static int add_part(int slot, struct cmd
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info = &state->parts[slot].info;
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- label_min = min_t(int, sizeof(info->volname) - 1,
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- sizeof(subpart->name));
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- strscpy(info->volname, subpart->name, label_min);
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+ strscpy(info->volname, subpart->name, sizeof(info->volname));
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snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
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strlcat(state->pp_buf, tmp, PAGE_SIZE);
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