From: David Laight <david.laight.linux@gmail.com>
To: Kees Cook <kees@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Josh Law <objecting@objecting.org>, Jens Axboe <axboe@kernel.dk>,
Davidlohr Bueso <dave@stgolabs.net>,
Stefan Haberland <sth@linux.ibm.com>,
Jan Hoeppner <hoeppner@linux.ibm.com>,
"Richard Russon (FlatCap)" <ldm@flatcap.org>,
Thorsten Blum <thorsten.blum@linux.dev>,
linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
linux-efi@vger.kernel.org, linux-s390@vger.kernel.org,
linux-ntfs-dev@lists.sourceforge.net,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] block: partitions: Replace pp_buf with struct seq_buf
Date: Sat, 21 Mar 2026 15:24:08 +0000 [thread overview]
Message-ID: <20260321152408.329cc48c@pumpkin> (raw)
In-Reply-To: <20260321004840.work.670-kees@kernel.org>
On Fri, 20 Mar 2026 17:48:44 -0700
Kees Cook <kees@kernel.org> wrote:
> In preparation for removing the strlcat API[1], replace the char *pp_buf
> with a struct seq_buf, which tracks the current write position and
> remaining space internally. This allows for:
>
> - Direct use of seq_buf_printf() in place of snprintf()+strlcat()
> pairs, eliminating local tmp buffers throughout.
and repeated scanning of the output buffer.
> - Adjacent strlcat() calls that build strings piece-by-piece
> (e.g., strlcat("["); strlcat(name); strlcat("]")) to be collapsed
> into single seq_buf_printf() calls.
> - Simpler call sites: seq_buf_puts() takes only the buffer and string,
> with no need to pass PAGE_SIZE at every call.
>
> The backing buffer allocation is unchanged (__get_free_page),
It might make sens to change that at the same time.
I'm not sure how big it needs to be either, 4k is a lot, 64k stupid.
Indeed, since the structure that contains the pointer is kmalloced
then just using an inlined array is probably enough.
Although the size would need to be a bit smaller to keep the kmalloc()
call below 4k (or even 2k - I'm sure that would be plenty...)
In any case the buffer can be allocated by alloc_partitions().
One further comment below.
But does all look a good idea to me.
> and the
> output path uses seq_buf_str() to NUL-terminate before passing to
> printk().
>
> Link: https://github.com/KSPP/linux/issues/370 [1]
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Josh Law <objecting@objecting.org>
> Signed-off-by: Kees Cook <kees@kernel.org>
> ---
> I couldn't help myself. Here's the full patch, as I suggested in
> https://lore.kernel.org/lkml/202603201230.74BBFFABAD@keescook/
> There are plenty more like this to do...
> ---
> block/partitions/check.h | 8 ++---
> block/partitions/core.c | 20 ++++++------
> block/partitions/acorn.c | 32 ++++++++----------
> block/partitions/aix.c | 21 +++++-------
> block/partitions/amiga.c | 35 +++++++++-----------
> block/partitions/atari.c | 12 +++----
> block/partitions/cmdline.c | 6 ++--
> block/partitions/efi.c | 2 +-
> block/partitions/ibm.c | 27 ++++++---------
> block/partitions/karma.c | 2 +-
> block/partitions/ldm.c | 4 +--
> block/partitions/mac.c | 4 +--
> block/partitions/msdos.c | 67 +++++++++++++-------------------------
> block/partitions/of.c | 6 ++--
> block/partitions/osf.c | 2 +-
> block/partitions/sgi.c | 2 +-
> block/partitions/sun.c | 2 +-
> block/partitions/sysv68.c | 9 ++---
> block/partitions/ultrix.c | 2 +-
> 19 files changed, 106 insertions(+), 157 deletions(-)
>
> diff --git a/block/partitions/check.h b/block/partitions/check.h
> index e5c1c61eb353..b0997467b61a 100644
> --- a/block/partitions/check.h
> +++ b/block/partitions/check.h
> @@ -1,6 +1,7 @@
> /* SPDX-License-Identifier: GPL-2.0 */
> #include <linux/pagemap.h>
> #include <linux/blkdev.h>
> +#include <linux/seq_buf.h>
> #include "../blk.h"
>
> /*
> @@ -20,7 +21,7 @@ struct parsed_partitions {
> int next;
> int limit;
> bool access_beyond_eod;
> - char *pp_buf;
> + struct seq_buf pp_buf;
> };
>
> typedef struct {
> @@ -37,12 +38,9 @@ static inline void
> put_partition(struct parsed_partitions *p, int n, sector_t from, sector_t size)
> {
> if (n < p->limit) {
> - char tmp[1 + BDEVNAME_SIZE + 10 + 1];
> -
> p->parts[n].from = from;
> p->parts[n].size = size;
> - snprintf(tmp, sizeof(tmp), " %s%d", p->name, n);
> - strlcat(p->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&p->pp_buf, " %s%d", p->name, n);
> }
> }
>
> diff --git a/block/partitions/core.c b/block/partitions/core.c
> index 740228750aaf..3b5928836c69 100644
> --- a/block/partitions/core.c
> +++ b/block/partitions/core.c
> @@ -123,16 +123,16 @@ static struct parsed_partitions *check_partition(struct gendisk *hd)
> state = allocate_partitions(hd);
> if (!state)
> return NULL;
> - state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
> - if (!state->pp_buf) {
> + state->pp_buf.buffer = (char *)__get_free_page(GFP_KERNEL);
> + if (!state->pp_buf.buffer) {
> free_partitions(state);
> return NULL;
> }
> - state->pp_buf[0] = '\0';
> + seq_buf_init(&state->pp_buf, state->pp_buf.buffer, PAGE_SIZE);
>
> state->disk = hd;
> strscpy(state->name, hd->disk_name);
> - snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
> + seq_buf_printf(&state->pp_buf, " %s:", state->name);
> if (isdigit(state->name[strlen(state->name)-1]))
> sprintf(state->name, "p");
>
> @@ -151,9 +151,9 @@ static struct parsed_partitions *check_partition(struct gendisk *hd)
>
> }
> if (res > 0) {
> - printk(KERN_INFO "%s", state->pp_buf);
> + printk(KERN_INFO "%s", seq_buf_str(&state->pp_buf));
>
> - free_page((unsigned long)state->pp_buf);
> + free_page((unsigned long)state->pp_buf.buffer);
> return state;
> }
> if (state->access_beyond_eod)
> @@ -164,12 +164,12 @@ static struct parsed_partitions *check_partition(struct gendisk *hd)
> if (err)
> res = err;
> if (res) {
> - strlcat(state->pp_buf,
> - " unable to read partition table\n", PAGE_SIZE);
> - printk(KERN_INFO "%s", state->pp_buf);
> + seq_buf_puts(&state->pp_buf,
> + " unable to read partition table\n");
> + printk(KERN_INFO "%s", seq_buf_str(&state->pp_buf));
Just put the string in the printk format:
printk(KERN_INFO "%s unable to read partition table\n",
seq_buf_str(&state->pp_buf));
Although I'm not sure that embedded '\n' get handled sensibly.
David
> }
>
> - free_page((unsigned long)state->pp_buf);
> + free_page((unsigned long)state->pp_buf.buffer);
> free_partitions(state);
> return ERR_PTR(res);
> }
> diff --git a/block/partitions/acorn.c b/block/partitions/acorn.c
> index d2fc122d7426..9f7389f174d0 100644
> --- a/block/partitions/acorn.c
> +++ b/block/partitions/acorn.c
> @@ -40,9 +40,7 @@ adfs_partition(struct parsed_partitions *state, char *name, char *data,
> (le32_to_cpu(dr->disc_size) >> 9);
>
> if (name) {
> - strlcat(state->pp_buf, " [", PAGE_SIZE);
> - strlcat(state->pp_buf, name, PAGE_SIZE);
> - strlcat(state->pp_buf, "]", PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, " [%s]", name);
> }
> put_partition(state, slot, first_sector, nr_sects);
> return dr;
> @@ -78,14 +76,14 @@ static int riscix_partition(struct parsed_partitions *state,
> if (!rr)
> return -1;
>
> - strlcat(state->pp_buf, " [RISCiX]", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " [RISCiX]");
>
>
> if (rr->magic == RISCIX_MAGIC) {
> unsigned long size = nr_sects > 2 ? 2 : nr_sects;
> int part;
>
> - strlcat(state->pp_buf, " <", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " <");
>
> put_partition(state, slot++, first_sect, size);
> for (part = 0; part < 8; part++) {
> @@ -94,13 +92,11 @@ static int riscix_partition(struct parsed_partitions *state,
> put_partition(state, slot++,
> le32_to_cpu(rr->part[part].start),
> le32_to_cpu(rr->part[part].length));
> - strlcat(state->pp_buf, "(", PAGE_SIZE);
> - strlcat(state->pp_buf, rr->part[part].name, PAGE_SIZE);
> - strlcat(state->pp_buf, ")", PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "(%s)", rr->part[part].name);
> }
> }
>
> - strlcat(state->pp_buf, " >\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " >\n");
> } else {
> put_partition(state, slot++, first_sect, nr_sects);
> }
> @@ -130,7 +126,7 @@ static int linux_partition(struct parsed_partitions *state,
> struct linux_part *linuxp;
> unsigned long size = nr_sects > 2 ? 2 : nr_sects;
>
> - strlcat(state->pp_buf, " [Linux]", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " [Linux]");
>
> put_partition(state, slot++, first_sect, size);
>
> @@ -138,7 +134,7 @@ static int linux_partition(struct parsed_partitions *state,
> if (!linuxp)
> return -1;
>
> - strlcat(state->pp_buf, " <", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " <");
> while (linuxp->magic == cpu_to_le32(LINUX_NATIVE_MAGIC) ||
> linuxp->magic == cpu_to_le32(LINUX_SWAP_MAGIC)) {
> if (slot == state->limit)
> @@ -148,7 +144,7 @@ static int linux_partition(struct parsed_partitions *state,
> le32_to_cpu(linuxp->nr_sects));
> linuxp ++;
> }
> - strlcat(state->pp_buf, " >", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " >");
>
> put_dev_sector(sect);
> return slot;
> @@ -293,7 +289,7 @@ int adfspart_check_ADFS(struct parsed_partitions *state)
> break;
> }
> }
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> }
> #endif
> @@ -366,7 +362,7 @@ int adfspart_check_ICS(struct parsed_partitions *state)
> return 0;
> }
>
> - strlcat(state->pp_buf, " [ICS]", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " [ICS]");
>
> for (slot = 1, p = (const struct ics_part *)data; p->size; p++) {
> u32 start = le32_to_cpu(p->start);
> @@ -400,7 +396,7 @@ int adfspart_check_ICS(struct parsed_partitions *state)
> }
>
> put_dev_sector(sect);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> }
> #endif
> @@ -460,7 +456,7 @@ int adfspart_check_POWERTEC(struct parsed_partitions *state)
> return 0;
> }
>
> - strlcat(state->pp_buf, " [POWERTEC]", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " [POWERTEC]");
>
> for (i = 0, p = (const struct ptec_part *)data; i < 12; i++, p++) {
> u32 start = le32_to_cpu(p->start);
> @@ -471,7 +467,7 @@ int adfspart_check_POWERTEC(struct parsed_partitions *state)
> }
>
> put_dev_sector(sect);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> }
> #endif
> @@ -542,7 +538,7 @@ int adfspart_check_EESOX(struct parsed_partitions *state)
>
> size = get_capacity(state->disk);
> put_partition(state, slot++, start, size - start);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> }
>
> return i ? 1 : 0;
> diff --git a/block/partitions/aix.c b/block/partitions/aix.c
> index a886cefbefbb..29b8f4cebb63 100644
> --- a/block/partitions/aix.c
> +++ b/block/partitions/aix.c
> @@ -173,24 +173,22 @@ int aix_partition(struct parsed_partitions *state)
> if (d) {
> struct lvm_rec *p = (struct lvm_rec *)d;
> u16 lvm_version = be16_to_cpu(p->version);
> - char tmp[64];
>
> if (lvm_version == 1) {
> int pp_size_log2 = be16_to_cpu(p->pp_size);
>
> pp_bytes_size = 1 << pp_size_log2;
> pp_blocks_size = pp_bytes_size / 512;
> - snprintf(tmp, sizeof(tmp),
> - " AIX LVM header version %u found\n",
> - lvm_version);
> + seq_buf_printf(&state->pp_buf,
> + " AIX LVM header version %u found\n",
> + lvm_version);
> vgda_len = be32_to_cpu(p->vgda_len);
> vgda_sector = be32_to_cpu(p->vgda_psn[0]);
> } else {
> - snprintf(tmp, sizeof(tmp),
> - " unsupported AIX LVM version %d found\n",
> - lvm_version);
> + seq_buf_printf(&state->pp_buf,
> + " unsupported AIX LVM version %d found\n",
> + lvm_version);
> }
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> put_dev_sector(sect);
> }
> if (vgda_sector && (d = read_part_sector(state, vgda_sector, §))) {
> @@ -251,14 +249,11 @@ int aix_partition(struct parsed_partitions *state)
> continue;
> }
> if (lp_ix == lvip[lv_ix].pps_per_lv) {
> - char tmp[70];
> -
> put_partition(state, lv_ix + 1,
> (i + 1 - lp_ix) * pp_blocks_size + psn_part1,
> lvip[lv_ix].pps_per_lv * pp_blocks_size);
> - snprintf(tmp, sizeof(tmp), " <%s>\n",
> - n[lv_ix].name);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, " <%s>\n",
> + n[lv_ix].name);
> lvip[lv_ix].lv_is_contiguous = 1;
> ret = 1;
> next_lp_ix = 1;
> diff --git a/block/partitions/amiga.c b/block/partitions/amiga.c
> index 506921095412..8325046a14eb 100644
> --- a/block/partitions/amiga.c
> +++ b/block/partitions/amiga.c
> @@ -81,13 +81,8 @@ int amiga_partition(struct parsed_partitions *state)
> /* blksize is blocks per 512 byte standard block */
> blksize = be32_to_cpu( rdb->rdb_BlockBytes ) / 512;
>
> - {
> - char tmp[7 + 10 + 1 + 1];
> -
> - /* Be more informative */
> - snprintf(tmp, sizeof(tmp), " RDSK (%d)", blksize * 512);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> - }
> + /* Be more informative */
> + seq_buf_printf(&state->pp_buf, " RDSK (%d)", blksize * 512);
> blk = be32_to_cpu(rdb->rdb_PartitionList);
> put_dev_sector(sect);
> for (part = 1; (s32) blk>0 && part<=16; part++, put_dev_sector(sect)) {
> @@ -179,27 +174,27 @@ int amiga_partition(struct parsed_partitions *state)
> {
> /* Be even more informative to aid mounting */
> char dostype[4];
> - char tmp[42];
>
> __be32 *dt = (__be32 *)dostype;
> *dt = pb->pb_Environment[16];
> if (dostype[3] < ' ')
> - snprintf(tmp, sizeof(tmp), " (%c%c%c^%c)",
> - dostype[0], dostype[1],
> - dostype[2], dostype[3] + '@' );
> + seq_buf_printf(&state->pp_buf,
> + " (%c%c%c^%c)",
> + dostype[0], dostype[1],
> + dostype[2],
> + dostype[3] + '@');
> else
> - snprintf(tmp, sizeof(tmp), " (%c%c%c%c)",
> - dostype[0], dostype[1],
> - dostype[2], dostype[3]);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> - snprintf(tmp, sizeof(tmp), "(res %d spb %d)",
> - be32_to_cpu(pb->pb_Environment[6]),
> - be32_to_cpu(pb->pb_Environment[4]));
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf,
> + " (%c%c%c%c)",
> + dostype[0], dostype[1],
> + dostype[2], dostype[3]);
> + seq_buf_printf(&state->pp_buf, "(res %d spb %d)",
> + be32_to_cpu(pb->pb_Environment[6]),
> + be32_to_cpu(pb->pb_Environment[4]));
> }
> res = 1;
> }
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
>
> rdb_done:
> return res;
> diff --git a/block/partitions/atari.c b/block/partitions/atari.c
> index 9655c728262a..2438d1448f38 100644
> --- a/block/partitions/atari.c
> +++ b/block/partitions/atari.c
> @@ -70,7 +70,7 @@ int atari_partition(struct parsed_partitions *state)
> }
>
> pi = &rs->part[0];
> - strlcat(state->pp_buf, " AHDI", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " AHDI");
> for (slot = 1; pi < &rs->part[4] && slot < state->limit; slot++, pi++) {
> struct rootsector *xrs;
> Sector sect2;
> @@ -89,7 +89,7 @@ int atari_partition(struct parsed_partitions *state)
> #ifdef ICD_PARTS
> part_fmt = 1;
> #endif
> - strlcat(state->pp_buf, " XGM<", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " XGM<");
> partsect = extensect = be32_to_cpu(pi->st);
> while (1) {
> xrs = read_part_sector(state, partsect, §2);
> @@ -128,14 +128,14 @@ int atari_partition(struct parsed_partitions *state)
> break;
> }
> }
> - strlcat(state->pp_buf, " >", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " >");
> }
> #ifdef ICD_PARTS
> if ( part_fmt!=1 ) { /* no extended partitions -> test ICD-format */
> pi = &rs->icdpart[0];
> /* sanity check: no ICD format if first partition invalid */
> if (OK_id(pi->id)) {
> - strlcat(state->pp_buf, " ICD<", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " ICD<");
> for (; pi < &rs->icdpart[8] && slot < state->limit; slot++, pi++) {
> /* accept only GEM,BGM,RAW,LNX,SWP partitions */
> if (!((pi->flg & 1) && OK_id(pi->id)))
> @@ -144,13 +144,13 @@ int atari_partition(struct parsed_partitions *state)
> be32_to_cpu(pi->st),
> be32_to_cpu(pi->siz));
> }
> - strlcat(state->pp_buf, " >", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " >");
> }
> }
> #endif
> put_dev_sector(sect);
>
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
>
> return 1;
> }
> diff --git a/block/partitions/cmdline.c b/block/partitions/cmdline.c
> index a2b1870c3fd4..4fd52ed154b4 100644
> --- a/block/partitions/cmdline.c
> +++ b/block/partitions/cmdline.c
> @@ -229,7 +229,6 @@ static int add_part(int slot, struct cmdline_subpart *subpart,
> struct parsed_partitions *state)
> {
> struct partition_meta_info *info;
> - char tmp[sizeof(info->volname) + 4];
>
> if (slot >= state->limit)
> return 1;
> @@ -244,8 +243,7 @@ static int add_part(int slot, struct cmdline_subpart *subpart,
>
> strscpy(info->volname, subpart->name, sizeof(info->volname));
>
> - snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "(%s)", info->volname);
>
> state->parts[slot].has_info = true;
>
> @@ -379,7 +377,7 @@ int cmdline_partition(struct parsed_partitions *state)
> cmdline_parts_set(parts, disk_size, state);
> cmdline_parts_verifier(1, state);
>
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
>
> return 1;
> }
> diff --git a/block/partitions/efi.c b/block/partitions/efi.c
> index 75474fb3848e..9865d59093fa 100644
> --- a/block/partitions/efi.c
> +++ b/block/partitions/efi.c
> @@ -751,6 +751,6 @@ int efi_partition(struct parsed_partitions *state)
> }
> kfree(ptes);
> kfree(gpt);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> }
> diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c
> index 9311ad5fb95d..54047e722a9d 100644
> --- a/block/partitions/ibm.c
> +++ b/block/partitions/ibm.c
> @@ -173,15 +173,13 @@ static int find_vol1_partitions(struct parsed_partitions *state,
> {
> sector_t blk;
> int counter;
> - char tmp[64];
> Sector sect;
> unsigned char *data;
> loff_t offset, size;
> struct vtoc_format1_label f1;
> int secperblk;
>
> - snprintf(tmp, sizeof(tmp), "VOL1/%8s:", name);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "VOL1/%8s:", name);
> /*
> * get start of VTOC from the disk label and then search for format1
> * and format8 labels
> @@ -219,7 +217,7 @@ static int find_vol1_partitions(struct parsed_partitions *state,
> blk++;
> data = read_part_sector(state, blk * secperblk, §);
> }
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
>
> if (!data)
> return -1;
> @@ -237,11 +235,9 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
> dasd_information2_t *info)
> {
> loff_t offset, geo_size, size;
> - char tmp[64];
> int secperblk;
>
> - snprintf(tmp, sizeof(tmp), "LNX1/%8s:", name);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "LNX1/%8s:", name);
> secperblk = blocksize >> 9;
> if (label->lnx.ldl_version == 0xf2) {
> size = label->lnx.formatted_blocks * secperblk;
> @@ -258,7 +254,7 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
> size = nr_sectors;
> if (size != geo_size) {
> if (!info) {
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> }
> if (!strcmp(info->type, "ECKD"))
> @@ -270,7 +266,7 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
> /* first and only partition starts in the first block after the label */
> offset = labelsect + secperblk;
> put_partition(state, 1, offset, size - offset);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> }
>
> @@ -282,7 +278,6 @@ static int find_cms1_partitions(struct parsed_partitions *state,
> sector_t labelsect)
> {
> loff_t offset, size;
> - char tmp[64];
> int secperblk;
>
> /*
> @@ -291,14 +286,12 @@ static int find_cms1_partitions(struct parsed_partitions *state,
> blocksize = label->cms.block_size;
> secperblk = blocksize >> 9;
> if (label->cms.disk_offset != 0) {
> - snprintf(tmp, sizeof(tmp), "CMS1/%8s(MDSK):", name);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "CMS1/%8s(MDSK):", name);
> /* disk is reserved minidisk */
> offset = label->cms.disk_offset * secperblk;
> size = (label->cms.block_count - 1) * secperblk;
> } else {
> - snprintf(tmp, sizeof(tmp), "CMS1/%8s:", name);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "CMS1/%8s:", name);
> /*
> * Special case for FBA devices:
> * If an FBA device is CMS formatted with blocksize > 512 byte
> @@ -314,7 +307,7 @@ static int find_cms1_partitions(struct parsed_partitions *state,
> }
>
> put_partition(state, 1, offset, size-offset);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> }
>
> @@ -391,11 +384,11 @@ int ibm_partition(struct parsed_partitions *state)
> */
> res = 1;
> if (info->format == DASD_FORMAT_LDL) {
> - strlcat(state->pp_buf, "(nonl)", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "(nonl)");
> size = nr_sectors;
> offset = (info->label_block + 1) * (blocksize >> 9);
> put_partition(state, 1, offset, size-offset);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> }
> } else
> res = 0;
> diff --git a/block/partitions/karma.c b/block/partitions/karma.c
> index 4d93512f4bd4..a4e3c5050177 100644
> --- a/block/partitions/karma.c
> +++ b/block/partitions/karma.c
> @@ -53,7 +53,7 @@ int karma_partition(struct parsed_partitions *state)
> }
> slot++;
> }
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> put_dev_sector(sect);
> return 1;
> }
> diff --git a/block/partitions/ldm.c b/block/partitions/ldm.c
> index 776b4ad95091..c0bdcae58a3e 100644
> --- a/block/partitions/ldm.c
> +++ b/block/partitions/ldm.c
> @@ -582,7 +582,7 @@ static bool ldm_create_data_partitions (struct parsed_partitions *pp,
> return false;
> }
>
> - strlcat(pp->pp_buf, " [LDM]", PAGE_SIZE);
> + seq_buf_puts(&pp->pp_buf, " [LDM]");
>
> /* Create the data partitions */
> list_for_each (item, &ldb->v_part) {
> @@ -597,7 +597,7 @@ static bool ldm_create_data_partitions (struct parsed_partitions *pp,
> part_num++;
> }
>
> - strlcat(pp->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&pp->pp_buf, "\n");
> return true;
> }
>
> diff --git a/block/partitions/mac.c b/block/partitions/mac.c
> index b02530d98629..df03ca428e15 100644
> --- a/block/partitions/mac.c
> +++ b/block/partitions/mac.c
> @@ -86,7 +86,7 @@ int mac_partition(struct parsed_partitions *state)
> if (blocks_in_map >= state->limit)
> blocks_in_map = state->limit - 1;
>
> - strlcat(state->pp_buf, " [mac]", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " [mac]");
> for (slot = 1; slot <= blocks_in_map; ++slot) {
> int pos = slot * secsize;
> put_dev_sector(sect);
> @@ -152,6 +152,6 @@ int mac_partition(struct parsed_partitions *state)
> #endif
>
> put_dev_sector(sect);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> }
> diff --git a/block/partitions/msdos.c b/block/partitions/msdos.c
> index 073be78ba0b0..200ea53ea6a2 100644
> --- a/block/partitions/msdos.c
> +++ b/block/partitions/msdos.c
> @@ -263,18 +263,11 @@ static void parse_solaris_x86(struct parsed_partitions *state,
> put_dev_sector(sect);
> return;
> }
> - {
> - char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1];
> -
> - snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> - }
> + seq_buf_printf(&state->pp_buf, " %s%d: <solaris:", state->name, origin);
> if (le32_to_cpu(v->v_version) != 1) {
> - char tmp[64];
> -
> - snprintf(tmp, sizeof(tmp), " cannot handle version %d vtoc>\n",
> - le32_to_cpu(v->v_version));
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf,
> + " cannot handle version %d vtoc>\n",
> + le32_to_cpu(v->v_version));
> put_dev_sector(sect);
> return;
> }
> @@ -282,12 +275,10 @@ static void parse_solaris_x86(struct parsed_partitions *state,
> max_nparts = le16_to_cpu(v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
> for (i = 0; i < max_nparts && state->next < state->limit; i++) {
> struct solaris_x86_slice *s = &v->v_slice[i];
> - char tmp[3 + 10 + 1 + 1];
>
> if (s->s_size == 0)
> continue;
> - snprintf(tmp, sizeof(tmp), " [s%d]", i);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, " [s%d]", i);
> /* solaris partitions are relative to current MS-DOS
> * one; must add the offset of the current partition */
> put_partition(state, state->next++,
> @@ -295,7 +286,7 @@ static void parse_solaris_x86(struct parsed_partitions *state,
> le32_to_cpu(s->s_size));
> }
> put_dev_sector(sect);
> - strlcat(state->pp_buf, " >\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " >\n");
> #endif
> }
>
> @@ -359,7 +350,6 @@ static void parse_bsd(struct parsed_partitions *state,
> Sector sect;
> struct bsd_disklabel *l;
> struct bsd_partition *p;
> - char tmp[64];
>
> l = read_part_sector(state, offset + 1, §);
> if (!l)
> @@ -369,8 +359,7 @@ static void parse_bsd(struct parsed_partitions *state,
> return;
> }
>
> - snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, " %s%d: <%s:", state->name, origin, flavour);
>
> if (le16_to_cpu(l->d_npartitions) < max_partitions)
> max_partitions = le16_to_cpu(l->d_npartitions);
> @@ -391,18 +380,16 @@ static void parse_bsd(struct parsed_partitions *state,
> /* full parent partition, we have it already */
> continue;
> if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
> - strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "bad subpartition - ignored\n");
> continue;
> }
> put_partition(state, state->next++, bsd_start, bsd_size);
> }
> put_dev_sector(sect);
> - if (le16_to_cpu(l->d_npartitions) > max_partitions) {
> - snprintf(tmp, sizeof(tmp), " (ignored %d more)",
> - le16_to_cpu(l->d_npartitions) - max_partitions);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> - }
> - strlcat(state->pp_buf, " >\n", PAGE_SIZE);
> + if (le16_to_cpu(l->d_npartitions) > max_partitions)
> + seq_buf_printf(&state->pp_buf, " (ignored %d more)",
> + le16_to_cpu(l->d_npartitions) - max_partitions);
> + seq_buf_puts(&state->pp_buf, " >\n");
> }
> #endif
>
> @@ -496,12 +483,7 @@ static void parse_unixware(struct parsed_partitions *state,
> put_dev_sector(sect);
> return;
> }
> - {
> - char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1];
> -
> - snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> - }
> + seq_buf_printf(&state->pp_buf, " %s%d: <unixware:", state->name, origin);
> p = &l->vtoc.v_slice[1];
> /* I omit the 0th slice as it is the same as whole disk. */
> while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
> @@ -515,7 +497,7 @@ static void parse_unixware(struct parsed_partitions *state,
> p++;
> }
> put_dev_sector(sect);
> - strlcat(state->pp_buf, " >\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " >\n");
> #endif
> }
>
> @@ -546,10 +528,7 @@ static void parse_minix(struct parsed_partitions *state,
> * the normal boot sector. */
> if (msdos_magic_present(data + 510) &&
> p->sys_ind == MINIX_PARTITION) { /* subpartition table present */
> - char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1];
> -
> - snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, " %s%d: <minix:", state->name, origin);
> for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
> if (state->next == state->limit)
> break;
> @@ -558,7 +537,7 @@ static void parse_minix(struct parsed_partitions *state,
> put_partition(state, state->next++,
> start_sect(p), nr_sects(p));
> }
> - strlcat(state->pp_buf, " >\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " >\n");
> }
> put_dev_sector(sect);
> #endif /* CONFIG_MINIX_SUBPARTITION */
> @@ -602,7 +581,7 @@ int msdos_partition(struct parsed_partitions *state)
> #ifdef CONFIG_AIX_PARTITION
> return aix_partition(state);
> #else
> - strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " [AIX]");
> return 0;
> #endif
> }
> @@ -629,7 +608,7 @@ int msdos_partition(struct parsed_partitions *state)
> fb = (struct fat_boot_sector *) data;
> if (slot == 1 && fb->reserved && fb->fats
> && fat_valid_media(fb->media)) {
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> put_dev_sector(sect);
> return 1;
> } else {
> @@ -678,9 +657,9 @@ int msdos_partition(struct parsed_partitions *state)
> n = min(size, max(sector_size, n));
> put_partition(state, slot, start, n);
>
> - strlcat(state->pp_buf, " <", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " <");
> parse_extended(state, start, size, disksig);
> - strlcat(state->pp_buf, " >", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, " >");
> continue;
> }
> put_partition(state, slot, start, size);
> @@ -688,12 +667,12 @@ int msdos_partition(struct parsed_partitions *state)
> if (p->sys_ind == LINUX_RAID_PARTITION)
> state->parts[slot].flags = ADDPART_FLAG_RAID;
> if (p->sys_ind == DM6_PARTITION)
> - strlcat(state->pp_buf, "[DM]", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "[DM]");
> if (p->sys_ind == EZD_PARTITION)
> - strlcat(state->pp_buf, "[EZD]", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "[EZD]");
> }
>
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
>
> /* second pass - output for each on a separate line */
> p = (struct msdos_partition *) (0x1be + data);
> diff --git a/block/partitions/of.c b/block/partitions/of.c
> index 4e760fdffb3f..c22b60661098 100644
> --- a/block/partitions/of.c
> +++ b/block/partitions/of.c
> @@ -36,7 +36,6 @@ static void add_of_partition(struct parsed_partitions *state, int slot,
> struct device_node *np)
> {
> struct partition_meta_info *info;
> - char tmp[sizeof(info->volname) + 4];
> const char *partname;
> int len;
>
> @@ -63,8 +62,7 @@ static void add_of_partition(struct parsed_partitions *state, int slot,
> partname = of_get_property(np, "name", &len);
> strscpy(info->volname, partname, sizeof(info->volname));
>
> - snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "(%s)", info->volname);
> }
>
> int of_partition(struct parsed_partitions *state)
> @@ -104,7 +102,7 @@ int of_partition(struct parsed_partitions *state)
> slot++;
> }
>
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
>
> return 1;
> }
> diff --git a/block/partitions/osf.c b/block/partitions/osf.c
> index 84560d0765ed..2a692584dba9 100644
> --- a/block/partitions/osf.c
> +++ b/block/partitions/osf.c
> @@ -81,7 +81,7 @@ int osf_partition(struct parsed_partitions *state)
> le32_to_cpu(partition->p_size));
> slot++;
> }
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> put_dev_sector(sect);
> return 1;
> }
> diff --git a/block/partitions/sgi.c b/block/partitions/sgi.c
> index b5ecddd5181a..2383ca63cd66 100644
> --- a/block/partitions/sgi.c
> +++ b/block/partitions/sgi.c
> @@ -79,7 +79,7 @@ int sgi_partition(struct parsed_partitions *state)
> }
> slot++;
> }
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> put_dev_sector(sect);
> return 1;
> }
> diff --git a/block/partitions/sun.c b/block/partitions/sun.c
> index 2419af76120f..92c645fcd2e0 100644
> --- a/block/partitions/sun.c
> +++ b/block/partitions/sun.c
> @@ -121,7 +121,7 @@ int sun_partition(struct parsed_partitions *state)
> }
> slot++;
> }
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> put_dev_sector(sect);
> return 1;
> }
> diff --git a/block/partitions/sysv68.c b/block/partitions/sysv68.c
> index 6f6257fd4eb4..470e0f9de7be 100644
> --- a/block/partitions/sysv68.c
> +++ b/block/partitions/sysv68.c
> @@ -54,7 +54,6 @@ int sysv68_partition(struct parsed_partitions *state)
> unsigned char *data;
> struct dkblk0 *b;
> struct slice *slice;
> - char tmp[64];
>
> data = read_part_sector(state, 0, §);
> if (!data)
> @@ -74,8 +73,7 @@ int sysv68_partition(struct parsed_partitions *state)
> return -1;
>
> slices -= 1; /* last slice is the whole disk */
> - snprintf(tmp, sizeof(tmp), "sysV68: %s(s%u)", state->name, slices);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "sysV68: %s(s%u)", state->name, slices);
> slice = (struct slice *)data;
> for (i = 0; i < slices; i++, slice++) {
> if (slot == state->limit)
> @@ -84,12 +82,11 @@ int sysv68_partition(struct parsed_partitions *state)
> put_partition(state, slot,
> be32_to_cpu(slice->blkoff),
> be32_to_cpu(slice->nblocks));
> - snprintf(tmp, sizeof(tmp), "(s%u)", i);
> - strlcat(state->pp_buf, tmp, PAGE_SIZE);
> + seq_buf_printf(&state->pp_buf, "(s%u)", i);
> }
> slot++;
> }
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> put_dev_sector(sect);
> return 1;
> }
> diff --git a/block/partitions/ultrix.c b/block/partitions/ultrix.c
> index 4aaa81043ca0..b4b9ddc57a5d 100644
> --- a/block/partitions/ultrix.c
> +++ b/block/partitions/ultrix.c
> @@ -39,7 +39,7 @@ int ultrix_partition(struct parsed_partitions *state)
> label->pt_part[i].pi_blkoff,
> label->pt_part[i].pi_nblocks);
> put_dev_sector(sect);
> - strlcat(state->pp_buf, "\n", PAGE_SIZE);
> + seq_buf_puts(&state->pp_buf, "\n");
> return 1;
> } else {
> put_dev_sector(sect);
next prev parent reply other threads:[~2026-03-21 15:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-21 0:48 [PATCH] block: partitions: Replace pp_buf with struct seq_buf Kees Cook
2026-03-21 12:08 ` Josh Law
2026-03-21 14:28 ` Jens Axboe
2026-03-21 14:32 ` Josh Law
2026-03-21 14:27 ` Jens Axboe
2026-03-21 15:24 ` David Laight [this message]
2026-03-23 8:51 ` Andy Shevchenko
2026-03-23 15:05 ` Andy Shevchenko
2026-03-23 20:08 ` David Laight
2026-03-23 22:29 ` Kees Cook
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