On the quest to remove all stack VLAs from the kernel[1] this changes the check_free_sectors() routine to use a kmalloc()ed buffer instead of a large VLA stack buffer.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qpxydaacu1rq...@mail.gmail.com Signed-off-by: Kees Cook <[email protected]> --- v2: kmalloc() instead of stack buffer (Boris) --- drivers/mtd/inftlmount.c | 23 ++++++++++++++++------- drivers/mtd/nftlmount.c | 23 ++++++++++++++++------- 2 files changed, 32 insertions(+), 14 deletions(-) diff --git a/drivers/mtd/inftlmount.c b/drivers/mtd/inftlmount.c index aab4f68bd36f..2d598412972d 100644 --- a/drivers/mtd/inftlmount.c +++ b/drivers/mtd/inftlmount.c @@ -334,28 +334,37 @@ static int memcmpb(void *a, int c, int n) static int check_free_sectors(struct INFTLrecord *inftl, unsigned int address, int len, int check_oob) { - u8 buf[SECTORSIZE + inftl->mbd.mtd->oobsize]; struct mtd_info *mtd = inftl->mbd.mtd; size_t retlen; - int i; + int i, ret; + u8 *buf; + + buf = kmalloc(SECTORSIZE + mtd->oobsize, GFP_KERNEL); + if (!buf) + return -1; + ret = -1; for (i = 0; i < len; i += SECTORSIZE) { if (mtd_read(mtd, address, SECTORSIZE, &retlen, buf)) - return -1; + goto out; if (memcmpb(buf, 0xff, SECTORSIZE) != 0) - return -1; + goto out; if (check_oob) { if(inftl_read_oob(mtd, address, mtd->oobsize, &retlen, &buf[SECTORSIZE]) < 0) - return -1; + goto out; if (memcmpb(buf + SECTORSIZE, 0xff, mtd->oobsize) != 0) - return -1; + goto out; } address += SECTORSIZE; } - return 0; + ret = 0; + +out: + kfree(buf); + return ret; } /* diff --git a/drivers/mtd/nftlmount.c b/drivers/mtd/nftlmount.c index a6fbfa4e5799..6281da3dadac 100644 --- a/drivers/mtd/nftlmount.c +++ b/drivers/mtd/nftlmount.c @@ -272,28 +272,37 @@ static int memcmpb(void *a, int c, int n) static int check_free_sectors(struct NFTLrecord *nftl, unsigned int address, int len, int check_oob) { - u8 buf[SECTORSIZE + nftl->mbd.mtd->oobsize]; struct mtd_info *mtd = nftl->mbd.mtd; size_t retlen; - int i; + int i, ret; + u8 *buf; + + buf = kmalloc(SECTORSIZE + mtd->oobsize, GFP_KERNEL); + if (!buf) + return -1; + ret = -1; for (i = 0; i < len; i += SECTORSIZE) { if (mtd_read(mtd, address, SECTORSIZE, &retlen, buf)) - return -1; + goto out; if (memcmpb(buf, 0xff, SECTORSIZE) != 0) - return -1; + goto out; if (check_oob) { if(nftl_read_oob(mtd, address, mtd->oobsize, &retlen, &buf[SECTORSIZE]) < 0) - return -1; + goto out; if (memcmpb(buf + SECTORSIZE, 0xff, mtd->oobsize) != 0) - return -1; + goto out; } address += SECTORSIZE; } - return 0; + ret = 0; + +out: + kfree(buf); + return ret; } /* NFTL_format: format a Erase Unit by erasing ALL Erase Zones in the Erase Unit and -- 2.7.4 -- Kees Cook Pixel Security
