{"id":"CVE-2026-68187","state":"PUBLISHED","title":"exec: fix unsigned loop counter wrap in transfer_args_to_stack()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nexec: fix unsigned loop counter wrap in transfer_args_to_stack()\n\nThe stop value is derived from bprm->p >> PAGE_SHIFT. The index variable\nis an unsigned long. If bprm->p drops below PAGE_SIZE and stop becomes\nzero the loop condition index >= stop is always true.\n\nAfter the index == 0 iteration the decrement wraps to ULONG_MAX and\nbprm->page[ULONG_MAX] reads sizeof(void *) bytes in front of the array.\nThe pointer has wrapped to -1. That garbage pointer is then passed to\nkmap_local_page() and PAGE_SIZE bytes are copied from wherever that\nlands into the stack of the process being created. And the loop doesn't\nterminate either...\n\nGetting there only requires bprm->p < PAGE_SIZE. On !MMU\nbprm_set_stack_limit() and bprm_hit_stack_limit() are empty. So the only\nconstraint on how far bprm->p is pushed down is valid_arg_len(), i.e.\nthat each individual string still fits in what is left.\n\nbprm->p starts at PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *) so a\nsingle argument or environment string of a little over 31 pages leaves\nit in the first page:\n\n  Oops - load access fault [#1]\n  CPU: 0 UID: 0 PID: 1 Comm: victim Not tainted 7.2.0-rc4 #1\n  epc : __memcpy+0xd4/0xf8\n   ra : transfer_args_to_stack+0xaa/0xae\n   s4 : ffffffffffffffff   s2 : 0000000000000000\n   a1 : ffffffdc98000000   a2 : 0000000000001000\n  status: 0000000a00001880 badaddr: ffffffdc98000000 cause: 0000000000000005\n  [<801a5324>] __memcpy+0xd4/0xf8\n  [<800d5f6a>] load_flat_binary+0x43a/0x65e\n  [<800a2de4>] bprm_execve+0x1d4/0x316\n  [<800a351a>] do_execveat_common+0x12e/0x138\n  [<800a3d44>] __riscv_sys_execve+0x38/0x4e\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nThis is an arcane bug but we should still fix it.\n\nCount down from MAX_ARG_PAGES so the loop ends when index reaches stop,\nstop == 0 included. The iterations performed are unchanged for every\nother value of stop.\n\nOnly CONFIG_MMU=n builds are affected, transfer_args_to_stack() is used\nby binfmt_flat and binfmt_elf_fdpic on nommu only.\n\nThe loop predates git history. commit 7e7ec6a93434\n(\"elf_fdpic_transfer_args_to_stack(): make it generic\") only moved it\nfrom binfmt_elf_fdpic.c into fs/exec.c and narrowed the copy to the used\npart of the first page. The condition and the decrement are unchanged\nfrom 2.6.12-rc2.","publishedAt":"2026-08-10T11:59:59.303Z","updatedAt":"2026-08-19T16:30:56.724Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"a9eb5c4949008034909bc34ecfa0843ecc1d0ab3","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"67cf5cdad823afb0530d6d0341fbf4ca07e93a09","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"66e20942890a383eb39b2009a2ceb4c2ebec37ef","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"c62bb00caba66e01fb578d5f0302f247dc64930a","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"dfc2a00742af4cb7251c1a8fbce4fbae3cc0de4e","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2bc6bf70d41055377f390d06f0f3521deb62fd3b","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"55fa2c7f2b15583d1a2fe1b5abcc24377359339f","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"16cc4f5c1c4b9e45eca7f7deefa5410a292db599","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/exec.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/exec.c"]}],"references":["https://git.kernel.org/stable/c/a9eb5c4949008034909bc34ecfa0843ecc1d0ab3","https://git.kernel.org/stable/c/67cf5cdad823afb0530d6d0341fbf4ca07e93a09","https://git.kernel.org/stable/c/66e20942890a383eb39b2009a2ceb4c2ebec37ef","https://git.kernel.org/stable/c/c62bb00caba66e01fb578d5f0302f247dc64930a","https://git.kernel.org/stable/c/dfc2a00742af4cb7251c1a8fbce4fbae3cc0de4e","https://git.kernel.org/stable/c/2bc6bf70d41055377f390d06f0f3521deb62fd3b","https://git.kernel.org/stable/c/55fa2c7f2b15583d1a2fe1b5abcc24377359339f","https://git.kernel.org/stable/c/16cc4f5c1c4b9e45eca7f7deefa5410a292db599"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/68xxx/CVE-2026-68187.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-68187","state":"PUBLISHED","datePublished":"2026-08-10T11:59:59.303Z","dateUpdated":"2026-08-19T16:30:56.724Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-30T09:28:09.373Z"},"containers":{"cna":{"title":"exec: fix unsigned loop counter wrap in transfer_args_to_stack()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nexec: fix unsigned loop counter wrap in transfer_args_to_stack()\n\nThe stop value is derived from bprm->p >> PAGE_SHIFT. The index variable\nis an unsigned long. If bprm->p drops below PAGE_SIZE and stop becomes\nzero the loop condition index >= stop is always true.\n\nAfter the index == 0 iteration the decrement wraps to ULONG_MAX and\nbprm->page[ULONG_MAX] reads sizeof(void *) bytes in front of the array.\nThe pointer has wrapped to -1. That garbage pointer is then passed to\nkmap_local_page() and PAGE_SIZE bytes are copied from wherever that\nlands into the stack of the process being created. And the loop doesn't\nterminate either...\n\nGetting there only requires bprm->p < PAGE_SIZE. On !MMU\nbprm_set_stack_limit() and bprm_hit_stack_limit() are empty. So the only\nconstraint on how far bprm->p is pushed down is valid_arg_len(), i.e.\nthat each individual string still fits in what is left.\n\nbprm->p starts at PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *) so a\nsingle argument or environment string of a little over 31 pages leaves\nit in the first page:\n\n  Oops - load access fault [#1]\n  CPU: 0 UID: 0 PID: 1 Comm: victim Not tainted 7.2.0-rc4 #1\n  epc : __memcpy+0xd4/0xf8\n   ra : transfer_args_to_stack+0xaa/0xae\n   s4 : ffffffffffffffff   s2 : 0000000000000000\n   a1 : ffffffdc98000000   a2 : 0000000000001000\n  status: 0000000a00001880 badaddr: ffffffdc98000000 cause: 0000000000000005\n  [<801a5324>] __memcpy+0xd4/0xf8\n  [<800d5f6a>] load_flat_binary+0x43a/0x65e\n  [<800a2de4>] bprm_execve+0x1d4/0x316\n  [<800a351a>] do_execveat_common+0x12e/0x138\n  [<800a3d44>] __riscv_sys_execve+0x38/0x4e\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nThis is an arcane bug but we should still fix it.\n\nCount down from MAX_ARG_PAGES so the loop ends when index reaches stop,\nstop == 0 included. The iterations performed are unchanged for every\nother value of stop.\n\nOnly CONFIG_MMU=n builds are affected, transfer_args_to_stack() is used\nby binfmt_flat and binfmt_elf_fdpic on nommu only.\n\nThe loop predates git history. commit 7e7ec6a93434\n(\"elf_fdpic_transfer_args_to_stack(): make it generic\") only moved it\nfrom binfmt_elf_fdpic.c into fs/exec.c and narrowed the copy to the used\npart of the first page. The condition and the decrement are unchanged\nfrom 2.6.12-rc2."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"a9eb5c4949008034909bc34ecfa0843ecc1d0ab3","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"67cf5cdad823afb0530d6d0341fbf4ca07e93a09","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"66e20942890a383eb39b2009a2ceb4c2ebec37ef","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"c62bb00caba66e01fb578d5f0302f247dc64930a","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"dfc2a00742af4cb7251c1a8fbce4fbae3cc0de4e","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2bc6bf70d41055377f390d06f0f3521deb62fd3b","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"55fa2c7f2b15583d1a2fe1b5abcc24377359339f","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"16cc4f5c1c4b9e45eca7f7deefa5410a292db599","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/exec.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/exec.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/a9eb5c4949008034909bc34ecfa0843ecc1d0ab3"},{"url":"https://git.kernel.org/stable/c/67cf5cdad823afb0530d6d0341fbf4ca07e93a09"},{"url":"https://git.kernel.org/stable/c/66e20942890a383eb39b2009a2ceb4c2ebec37ef"},{"url":"https://git.kernel.org/stable/c/c62bb00caba66e01fb578d5f0302f247dc64930a"},{"url":"https://git.kernel.org/stable/c/dfc2a00742af4cb7251c1a8fbce4fbae3cc0de4e"},{"url":"https://git.kernel.org/stable/c/2bc6bf70d41055377f390d06f0f3521deb62fd3b"},{"url":"https://git.kernel.org/stable/c/55fa2c7f2b15583d1a2fe1b5abcc24377359339f"},{"url":"https://git.kernel.org/stable/c/16cc4f5c1c4b9e45eca7f7deefa5410a292db599"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-19T16:30:56.724Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.10.265"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.15.216"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.148"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.101"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}