{ "data_version": "4.0", "data_type": "CVE", "data_format": "MITRE", "CVE_data_meta": { "ID": "CVE-2024-45025", "ASSIGNER": "cve@kernel.org", "STATE": "PUBLIC" }, "description": { "description_data": [ { "lang": "eng", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfix bitmap corruption on close_range() with CLOSE_RANGE_UNSHARE\n\ncopy_fd_bitmaps(new, old, count) is expected to copy the first\ncount/BITS_PER_LONG bits from old->full_fds_bits[] and fill\nthe rest with zeroes. What it does is copying enough words\n(BITS_TO_LONGS(count/BITS_PER_LONG)), then memsets the rest.\nThat works fine, *if* all bits past the cutoff point are\nclear. Otherwise we are risking garbage from the last word\nwe'd copied.\n\nFor most of the callers that is true - expand_fdtable() has\ncount equal to old->max_fds, so there's no open descriptors\npast count, let alone fully occupied words in ->open_fds[],\nwhich is what bits in ->full_fds_bits[] correspond to.\n\nThe other caller (dup_fd()) passes sane_fdtable_size(old_fdt, max_fds),\nwhich is the smallest multiple of BITS_PER_LONG that covers all\nopened descriptors below max_fds. In the common case (copying on\nfork()) max_fds is ~0U, so all opened descriptors will be below\nit and we are fine, by the same reasons why the call in expand_fdtable()\nis safe.\n\nUnfortunately, there is a case where max_fds is less than that\nand where we might, indeed, end up with junk in ->full_fds_bits[] -\nclose_range(from, to, CLOSE_RANGE_UNSHARE) with\n\t* descriptor table being currently shared\n\t* 'to' being above the current capacity of descriptor table\n\t* 'from' being just under some chunk of opened descriptors.\nIn that case we end up with observably wrong behaviour - e.g. spawn\na child with CLONE_FILES, get all descriptors in range 0..127 open,\nthen close_range(64, ~0U, CLOSE_RANGE_UNSHARE) and watch dup(0) ending\nup with descriptor #128, despite #64 being observably not open.\n\nThe minimally invasive fix would be to deal with that in dup_fd().\nIf this proves to add measurable overhead, we can go that way, but\nlet's try to fix copy_fd_bitmaps() first.\n\n* new helper: bitmap_copy_and_expand(to, from, bits_to_copy, size).\n* make copy_fd_bitmaps() take the bitmap size in words, rather than\nbits; it's 'count' argument is always a multiple of BITS_PER_LONG,\nso we are not losing any information, and that way we can use the\nsame helper for all three bitmaps - compiler will see that count\nis a multiple of BITS_PER_LONG for the large ones, so it'll generate\nplain memcpy()+memset().\n\nReproducer added to tools/testing/selftests/core/close_range_test.c" } ] }, "problemtype": { "problemtype_data": [ { "description": [ { "lang": "eng", "value": "n/a" } ] } ] }, "affects": { "vendor": { "vendor_data": [ { "vendor_name": "Linux", "product": { "product_data": [ { "product_name": "Linux", "version": { "version_data": [ { "version_affected": "<", "version_name": "1da177e4c3f4", "version_value": "ee501f827f3d" }, { "version_value": "not down converted", "x_cve_json_5_version_data": { "versions": [ { "version": "4.19.321", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.4.283", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.10.225", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.15.166", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.1.107", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.6.48", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.10.7", "lessThanOrEqual": "6.10.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.11", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ], "defaultStatus": "affected" } } ] } } ] } } ] } }, "references": { "reference_data": [ { "url": "https://git.kernel.org/stable/c/ee501f827f3db02d4e599afbbc1a7f8b792d05d7", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/ee501f827f3db02d4e599afbbc1a7f8b792d05d7" }, { "url": "https://git.kernel.org/stable/c/e807487a1d5fd5d941f26578ae826ca815dbfcd6", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/e807487a1d5fd5d941f26578ae826ca815dbfcd6" }, { "url": "https://git.kernel.org/stable/c/fe5bf14881701119aeeda7cf685f3c226c7380df", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/fe5bf14881701119aeeda7cf685f3c226c7380df" }, { "url": "https://git.kernel.org/stable/c/5053581fe5dfb09b58c65dd8462bf5dea71f41ff", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/5053581fe5dfb09b58c65dd8462bf5dea71f41ff" }, { "url": "https://git.kernel.org/stable/c/8cad3b2b3ab81ca55f37405ffd1315bcc2948058", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/8cad3b2b3ab81ca55f37405ffd1315bcc2948058" }, { "url": "https://git.kernel.org/stable/c/dd72ae8b0fce9c0bbe9582b9b50820f0407f8d8a", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/dd72ae8b0fce9c0bbe9582b9b50820f0407f8d8a" }, { "url": "https://git.kernel.org/stable/c/c69d18f0ac7060de724511537810f10f29a27958", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/c69d18f0ac7060de724511537810f10f29a27958" }, { "url": "https://git.kernel.org/stable/c/9a2fa1472083580b6c66bdaf291f591e1170123a", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/9a2fa1472083580b6c66bdaf291f591e1170123a" } ] }, "generator": { "engine": "bippy-c9c4e1df01b2" } }