{"id":"CVE-2026-93048","state":"PUBLISHED","title":"mtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition()\n\nmtd_add_partition() does not reject the special offset value\nMTDPART_OFS_RETAIN (-3), which leads to a WARN_ON in\nadd_mtd_device() when called through the BLKPG ioctl on NAND\ndevices. The RETAIN value depends on cur_offset being the end of\nthe previous partition, but in the dynamic partition path\ncur_offset equals the offset argument itself, causing undefined\nbehavior.\n\nCommit 5daa7b21496a (\"mtd: prepare partition add and del functions\nfor ioctl requests\") introduced mtd_add_partition() and correctly\nrejected MTDPART_OFS_APPEND (-1) and MTDPART_OFS_NXTBLK (-2),\nsince those special offsets rely on cur_offset tracking the\nprevious partition's end. However, commit 1a31368bf92e (\"mtd: add a flags\nfor partitions which should just leave smth. after them\")\nlater added MTDPART_OFS_RETAIN (-3) for the static\npartition table path without updating mtd_add_partition() to\nalso reject this value.\n\nWith offset=-3 passed via BLKPG, the RETAIN size calculation in\nallocate_partition() underflows (parent_size - 0xFFFFFFFFFFFFFFFD\n= parent_size + 3). If the underflow result does not appear to\nleave enough space, allocate_partition() jumps to out_register via\ngoto, skipping erasesize initialization. This results in\nerasesize=0, which triggers:\n\nWARN_ON((!mtd->erasesize || !master->_erase) &&\n\t\t!(mtd->flags & MTD_NO_ERASE))\n\nin add_mtd_device(). If the underflow result appears to leave\nenough space, a bogus partition size is calculated, but the\n\"out of reach\" sanity check catches the invalid offset and\ncreates a disabled empty partition (offset=0, size=0) instead\nof returning an error.\n\nFix this by adding MTDPART_OFS_RETAIN to the rejection list in\nmtd_add_partition(), consistent with the existing handling of\nAPPEND and NXTBLK.","publishedAt":"2026-09-17T16:10:39.008Z","updatedAt":"2026-10-19T09:04:43.363Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"701c3ae7273e1adc20db5d97c42e0139b479f16b","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"6aaab2ace3f7b55733d904e5549acf8405f03642","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"181c1bff940e7d3e34ca485d37e3cdbfe409203c","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"a536eb57be58442b19398b2783071007ecfb1735","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"e204e5c49a012f99638633fdbd773e3c86260053","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"398aca2f90122d5abbabff1079deaeb885fe9e40","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"c645f6dd1af2ecc70fd3578e141f2f71fa9e4eff","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"b759d5bb6265419344ee9729fd0dc07ad85719d8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/mtd/mtdpart.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.2","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/mtd/mtdpart.c"]}],"references":["https://git.kernel.org/stable/c/701c3ae7273e1adc20db5d97c42e0139b479f16b","https://git.kernel.org/stable/c/6aaab2ace3f7b55733d904e5549acf8405f03642","https://git.kernel.org/stable/c/181c1bff940e7d3e34ca485d37e3cdbfe409203c","https://git.kernel.org/stable/c/a536eb57be58442b19398b2783071007ecfb1735","https://git.kernel.org/stable/c/e204e5c49a012f99638633fdbd773e3c86260053","https://git.kernel.org/stable/c/398aca2f90122d5abbabff1079deaeb885fe9e40","https://git.kernel.org/stable/c/c645f6dd1af2ecc70fd3578e141f2f71fa9e4eff","https://git.kernel.org/stable/c/b759d5bb6265419344ee9729fd0dc07ad85719d8"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/93xxx/CVE-2026-93048.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93048","state":"PUBLISHED","datePublished":"2026-09-17T16:10:39.008Z","dateUpdated":"2026-10-19T09:04:43.363Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-17T15:57:05.658Z"},"containers":{"cna":{"title":"mtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition()\n\nmtd_add_partition() does not reject the special offset value\nMTDPART_OFS_RETAIN (-3), which leads to a WARN_ON in\nadd_mtd_device() when called through the BLKPG ioctl on NAND\ndevices. The RETAIN value depends on cur_offset being the end of\nthe previous partition, but in the dynamic partition path\ncur_offset equals the offset argument itself, causing undefined\nbehavior.\n\nCommit 5daa7b21496a (\"mtd: prepare partition add and del functions\nfor ioctl requests\") introduced mtd_add_partition() and correctly\nrejected MTDPART_OFS_APPEND (-1) and MTDPART_OFS_NXTBLK (-2),\nsince those special offsets rely on cur_offset tracking the\nprevious partition's end. However, commit 1a31368bf92e (\"mtd: add a flags\nfor partitions which should just leave smth. after them\")\nlater added MTDPART_OFS_RETAIN (-3) for the static\npartition table path without updating mtd_add_partition() to\nalso reject this value.\n\nWith offset=-3 passed via BLKPG, the RETAIN size calculation in\nallocate_partition() underflows (parent_size - 0xFFFFFFFFFFFFFFFD\n= parent_size + 3). If the underflow result does not appear to\nleave enough space, allocate_partition() jumps to out_register via\ngoto, skipping erasesize initialization. This results in\nerasesize=0, which triggers:\n\nWARN_ON((!mtd->erasesize || !master->_erase) &&\n\t\t!(mtd->flags & MTD_NO_ERASE))\n\nin add_mtd_device(). If the underflow result appears to leave\nenough space, a bogus partition size is calculated, but the\n\"out of reach\" sanity check catches the invalid offset and\ncreates a disabled empty partition (offset=0, size=0) instead\nof returning an error.\n\nFix this by adding MTDPART_OFS_RETAIN to the rejection list in\nmtd_add_partition(), consistent with the existing handling of\nAPPEND and NXTBLK."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"701c3ae7273e1adc20db5d97c42e0139b479f16b","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"6aaab2ace3f7b55733d904e5549acf8405f03642","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"181c1bff940e7d3e34ca485d37e3cdbfe409203c","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"a536eb57be58442b19398b2783071007ecfb1735","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"e204e5c49a012f99638633fdbd773e3c86260053","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"398aca2f90122d5abbabff1079deaeb885fe9e40","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"c645f6dd1af2ecc70fd3578e141f2f71fa9e4eff","versionType":"git"},{"version":"1a31368bf92ef2a7da3ba379672c405bd2751df9","status":"affected","lessThan":"b759d5bb6265419344ee9729fd0dc07ad85719d8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/mtd/mtdpart.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.2","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/mtd/mtdpart.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/701c3ae7273e1adc20db5d97c42e0139b479f16b"},{"url":"https://git.kernel.org/stable/c/6aaab2ace3f7b55733d904e5549acf8405f03642"},{"url":"https://git.kernel.org/stable/c/181c1bff940e7d3e34ca485d37e3cdbfe409203c"},{"url":"https://git.kernel.org/stable/c/a536eb57be58442b19398b2783071007ecfb1735"},{"url":"https://git.kernel.org/stable/c/e204e5c49a012f99638633fdbd773e3c86260053"},{"url":"https://git.kernel.org/stable/c/398aca2f90122d5abbabff1079deaeb885fe9e40"},{"url":"https://git.kernel.org/stable/c/c645f6dd1af2ecc70fd3578e141f2f71fa9e4eff"},{"url":"https://git.kernel.org/stable/c/b759d5bb6265419344ee9729fd0dc07ad85719d8"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:04:43.363Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}