From: Jinjie Ruan <ruanjinjie@huawei.com> mainline inclusion from mainline-v7.3-rc1 commit fa40f9dbdd4af53e7445d9135b5b207eb8adf372 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19096 CVE: CVE-2026-89962 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Sashiko AI review pointed out the following issue. The __merge_memory_ranges() function incorrectly handles overlapping memory ranges when merging them. Although sort_memory_ranges() sorts all ranges by their start address in ascending order beforehand, the merge logic remains defective in two ways: 1. It compares the current range's start against the previous element (i-1) instead of the running target index (idx) 2. It unconditionally overwrites 'ranges[idx].end' with 'ranges[i].end'. This logic flaw leads to critical memory truncation when a larger memory range completely subsumes subsequent smaller ranges. For example, consider a sorted input array with three ranges: Range A (idx=0): [0x1000 - 0x9000] Range B (i=1): [0x2000 - 0x5000] (completely inside Range A) Range C (i=2): [0x6000 - 0x8000] (completely inside Range A) 1. When i=1 (Range B): ranges[1].start (0x2000) <= ranges[0].end + 1 (0x9001) is TRUE. The code executes: ranges[0].end = ranges[1].end, which erroneously shrinks Range A's end from 0x9000 down to 0x5000. 2. When i=2 (Range C): ranges[2].start (0x6000) <= ranges[1].end + 1 (0x5001) is FALSE. The code falls into the else block, creating a broken new range. As a result, valid memory fragments [0x5001 - 0x5fff] and [0x8001 - 0x9000] are completely lost from the kexec exclude lists, potentially allowing the crash kernel to overwrite active memory, causing data corruption or crashes. Fix this by ensuring the start of the current range is compared against the end of the active merged range (idx), and use max() to safely prevent the outer boundary from being truncated. Cc: stable@vger.kernel.org Fixes: 180adfc532a8 ("powerpc/kexec_file: Add helper functions for getting memory ranges") Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Link: https://patch.msgid.link/20260729012948.2797865-4-ruanjinjie@huawei.com Conflicts: arch/powerpc/kexec/ranges.c [Context conflict] Signed-off-by: Tengda Wu <wutengda2@huawei.com> --- arch/powerpc/kexec/ranges.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/kexec/ranges.c b/arch/powerpc/kexec/ranges.c index fb3e12f15214..ef025eea27e8 100644 --- a/arch/powerpc/kexec/ranges.c +++ b/arch/powerpc/kexec/ranges.c @@ -20,6 +20,7 @@ #include <linux/kexec.h> #include <linux/of.h> #include <linux/slab.h> +#include <linux/minmax.h> #include <asm/sections.h> #include <asm/kexec_ranges.h> @@ -101,19 +102,16 @@ static void __merge_memory_ranges(struct crash_mem *mem_rngs) struct range *ranges; int i, idx; - if (!mem_rngs) + if (!mem_rngs || mem_rngs->nr_ranges <= 1) return; idx = 0; - ranges = &(mem_rngs->ranges[0]); + ranges = mem_rngs->ranges; for (i = 1; i < mem_rngs->nr_ranges; i++) { - if (ranges[i].start <= (ranges[i-1].end + 1)) - ranges[idx].end = ranges[i].end; + if (ranges[i].start <= (ranges[idx].end + 1)) + ranges[idx].end = max(ranges[idx].end, ranges[i].end); else { idx++; - if (i == idx) - continue; - ranges[idx] = ranges[i]; } } -- 2.34.1